Merge request variables missing

In this ticket, I describe an issue where the codecov pipeline fails when a merge request is submitted, due to a configuration variable being missing. The variable is not masked nor protected, so it’s unclear (to me) what is causing the variable not to be set.

I’ve read through the help on variables and searched the web and this forum for others experiencing the same problem, but I can’t find any relevant resources.

Can someone provide an explanation (or reference one) about when a variable would be suppressed?

Is there a solution, other than using another channel, to configure variables for Merge Request runs?

Bump. This issue also affects the importlib-resources project.