osTicket Version v1.12.5
Web Server Software Apache/2.4.39 (Win64) OpenSSL/1.1.1b PHP/7.3.4
MySQL Version 5.5.37
PHP Version 7.3.4

Recently seeing this error, started a few days ago:

[SELECT COUNT(DISTINCT CASE WHEN A1.number IS NOT NULL THEN A1.ticket_id END) AS q15, COUNT(DISTINCT CASE WHEN A1.number IS NOT NULL AND A1.ticket_id = Z1.ticket_id THEN A1.ticket_id END) AS q16, COUNT(DISTINCT CASE WHEN A1.number IS NOT NULL AND A1.ticket_id = Z1.ticket_id THEN A1.ticket_id END) AS q17, COUNT(DISTINCT CASE WHEN A1.ticket_id = Z1.ticket_id THEN A1.ticket_id END) AS q18, COUNT(DISTINCT CASE WHEN A2.state = 'open' THEN A1.ticket_id END) AS q1, COUNT(DISTINCT CASE WHEN A2.state = 'open' AND A2.state = 'open' AND A1.isanswered = '0' THEN A1.ticket_id END) AS q2, COUNT(DISTINCT CASE WHEN (A1.team_id IN (2) OR A1.staff_id IN (2)) AND A2.state = 'open' AND (A1.team_id IN (2) OR A1.staff_id IN (2)) AND A2.state = 'open' AND A1.staff_id IN (2) THEN A1.ticket_id END) AS q6, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2020-04-10 00:00:00' AND '2020-04-10 23:59:59' THEN A1.ticket_id END) AS q9, COUNT(DISTINCT CASE WHEN A2.state = 'open' AND A2.state = 'open' AND A1.isanswered = '1' THEN A1.ticket_id END) AS q3, COUNT(DISTINCT CASE WHEN (A1.team_id IN (2) OR A1.staff_id IN (2)) AND A2.state = 'open' AND (A1.team_id IN (2) OR A1.staff_id IN (2)) AND A2.state = 'open' AND NOT A1.staff_id IN (2) THEN A1.ticket_id END) AS q7, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2020-04-09 00:00:00' AND '2020-04-09 23:59:59' THEN A1.ticket_id END) AS q10, COUNT(DISTINCT CASE WHEN A2.state = 'open' AND A2.state = 'open' AND A1.isoverdue = '1' THEN A1.ticket_id END) AS q4, COUNT(DISTINCT CASE WHEN (A1.team_id IN (2) OR A1.staff_id IN (2)) AND A2.state = 'open' THEN A1.ticket_id END) AS q5, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2020-04-06 00:00:00' AND '2020-04-12 23:59:59' THEN A1.ticket_id END) AS q11, COUNT(DISTINCT CASE WHEN A2.state = 'closed' THEN A1.ticket_id END) AS q8, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2020-04-01 00:00:00' AND '2020-04-30 23:59:59' THEN A1.ticket_id END) AS q12, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2020-04-01 00:00:00' AND '2020-06-30 23:59:59' THEN A1.ticket_id END) AS q13, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2020-01-01 00:00:00' AND '2020-12-31 23:59:59' THEN A1.ticket_id END) AS q14 FROM ost_ticket A1 JOIN ost_ticket_status A2 ON (A1.status_id = A2.id) LEFT JOIN ost_thread A3 ON (A3.object_type = 'T' AND A1.ticket_id = A3.object_id) LEFT JOIN ost_thread_referral A4 ON (A3.id = A4.thread_id) LEFT JOIN ost_staff A5 ON (A4.object_type = 'S' AND A4.object_id = A5.staff_id) LEFT JOIN ost_team A6 ON (A4.object_type = 'E' AND A4.object_id = A6.team_id) LEFT JOIN ost_department A7 ON (A4.object_type = 'D' AND A4.object_id = A7.id) WHERE (A2.state = 'open' AND (A1.staff_id = 2 OR A5.staff_id = 2 OR A1.team_id IN (2) OR A6.team_id IN (2))) OR (A2.state IN ('open', 'closed') AND (A1.dept_id IN (4, 5) OR A7.id IN (4, 5)))]

Unknown column 'Z1.ticket_id' in 'field list' 
---- Backtrace ---- 
#0 C:\xampp\htdocs\helpdesk\include\mysqli.php(200): osTicket->logDBError('DB Error #1054', '[SELECT COUNT(D...') 
#1 C:\xampp\htdocs\helpdesk\include\class.orm.php(3457): db_query('SELECT COUNT(DI...', true, true) 
#2 C:\xampp\htdocs\helpdesk\include\class.orm.php(3504): MySqlExecutor->execute() 
#3 C:\xampp\htdocs\helpdesk\include\class.orm.php(2087): MySqlExecutor->getArray() 
#4 C:\xampp\htdocs\helpdesk\include\class.orm.php(2037): HashArrayIterator->{closure}() 
#5 C:\xampp\htdocs\helpdesk\include\class.orm.php(2016): CallbackSimpleIterator->next() 
#6 C:\xampp\htdocs\helpdesk\include\class.orm.php(2025): CallbackSimpleIterator->rewind() 
#7 C:\xampp\htdocs\helpdesk\include\class.orm.php(1697): CallbackSimpleIterator->valid() 
#8 C:\xampp\htdocs\helpdesk\include\class.orm.php(1707): CachedResultSet->fillTo(9223372036854775807) 
#9 C:\xampp\htdocs\helpdesk\include\class.orm.php(1330): CachedResultSet->asArray() 
#10 C:\xampp\htdocs\helpdesk\include\class.orm.php(1353): QuerySet->all() 
#11 C:\xampp\htdocs\helpdesk\include\class.search.php(925): QuerySet->one() 
#12 C:\xampp\htdocs\helpdesk\include\ajax.search.php(397): SavedQueue::counts(Object(StaffSession), true, Array) 
#13 C:\xampp\htdocs\helpdesk\include\class.dispatcher.php(145): SearchAjaxAPI->collectQueueCounts() 
#14 C:\xampp\htdocs\helpdesk\include\class.dispatcher.php(38): UrlMatcher->dispatch('counts', Array) 
#15 C:\xampp\htdocs\helpdesk\include\class.dispatcher.php(120): Dispatcher->resolve('counts', Array) 
#16 C:\xampp\htdocs\helpdesk\include\class.dispatcher.php(38): UrlMatcher->dispatch('/queue/counts', NULL) 
#17 C:\xampp\htdocs\helpdesk\scp\ajax.php(289): Dispatcher->resolve('/queue/counts') 
#18 {main}

Very little custom fields or entries, everything was working fine and no changes made in the past few months. Was on 1.12.1 and after I saw these errors, upgraded to 1.12.5. Errors disappeared for half a day but has returned. Any help would be appreciated.