This means it is not able to find it in JARs I believe

which is logical

it is generated on the fly

To sum up. I need to investigate it. please fill in github issue with the minimum reproducible code. Usually, tbh I resolve the issue regarding MockK very slow these days. I became a tech lead at my work and doing a lot of responsibilities of team leader till we hire him. Alike I spend weekend per month to tackle with a bunch of issues. But will see what can be done if it is really a blocker for you and other users.