Hi @fredrambert
Hope you found the resolution based on your last comment.
We had processing rules to concatenate certain context variables and build a string that sets the page name.
When these context vars are set in the trackAction() call, it completes the rule for a pageName and the pageName gets assigned. The solution is to remove the building blocks that sets pageName if there are OR make adjustments in processing rule such that pageName is not set for a trackAction call.
I shall go back and check my notes on the exact changes we did if you still would like to know.
Best,