Following some assistance from other folk in the community, I have evolved my original query to as per the below, which I want to use to pull issues belonging to either of the fix versions IDs.
project = CC AND issuetype in (Story, Task) AND (labels != TechImprovement OR labels is EMPTY) AND fixVersion is fixVersion in (78760, 74907)
Unfortunately, it isn't quite working and Jira is returning the following error: "Error in the JQL Query: Expecting either 'OR' or 'AND' but got 'in'. (line 1, character 125)"
Thanks in advance!
PS. I was forced to create a new thread as the board wasn't accepting my replies in my other thread