Hmm, I’m not able to replicate the problem with your steps above. To clarify you click on the ... to select the custom comskip ini and then click “Cancel” instead of “Open”?
Could you capture a video of the steps to replicate it? I suspect it may be some other settings which is throwing it off.
EDIT: If you can please attach your mcebuddy.conf file also so I can replicate the exact setup.