I just stumbled over the fact that in sketch view some constraints are not documented with symbols and therefore cannot be deleted. Is there a way to make them visible or to somehow select them?
@HaroldL thanks for pointing to that dialog box!
I had never seen it and spent 15 min. trying to find it, only to realize that it's apparently only available using the 'classic' menus (which I had not used for years).
The post above actually pointed into that direction, if you took it word for word.