This is often related to options such as external virtual intersection and position of the bent sheet metal on tangent for example which makes a certain angle impossible.
https://i.imgur.com/2AFipl7.png
If you change these options and that should solve your problem
Thank you very much. Indeed, I modified these options and it works.
Have a nice day.
It's a logical option, no angle less than 90° possible by having the tangent rib, because it's not possible to be tangent. But the 1st time we look in vain for why it doesn't work.