I have a query which returns the count of a status that needs some very complex work to calculate. The user wants to drill down into that list, and I thought the easiest way
You need to set group_concat_max_len to a higher value. This can be done on a session or global level. The following query sets the max length to 10,000 for the rest of the queries in that session:
SET SESSION group_concat_max_len = 10000;
What you're running into is the group_concat default max of 1024.