As we are unable to search custom fields correctly in a "contains" way (e.g. "show all tickets where CustomFields CONTAINS 'something'") we've been putting the 3rd-party ticket references in the description, so we can find it:
Ticket ID: 12345
This is the full description of the ticket...
If I now type in 12345 into the search/command bar, it finds the Issue with that text in it.
If, however, we have multiple ticket ID's, it fails:
Ticket ID: 12345,67890
This is another ticket with two numbers in it
When I search for 67890 nothing is returned.
When I search for 12345 nothing is returned.
It's just text - I don't see why a comma in the description is being handled any different to any other character.