Looking at the examples it looks like the smoothing groups are off. I’ve seen the same problem on geometry where the smoothing group was bonked and the triangulation would show up in the light map.
Can you post the normal map?
If it is an issue with the normal map then the flaw will show up clearly and if not then more than likely it’s a smoothing group problem.
When you export the model was included smoothing groups checked as to what needed to be exported?
This one caught me more than a few times and an edge cut like that does not really say an normal map problem to me.