This has been happening to me in 2018 sp3 of Solidcrap I mean Solidworks.

I have been making sketchs the same for years.... and years and NEVER have this problem - upgraded to 2018 sp3 and

I just copied a WORKING sketch into a BRAND NEW - no feature sketch and get the

Result would be zero thickness geometry.

Nothing in the sketch should be causing this. - It's actually already working in a previous feature...

Has anyone else had this issue - and do you have a solution?

I can rework the sketch - e.g. re-sketch it. but that is just a waste of time and I shouldn't have to do it!