In short this is probably bad Topology causing Subdivision surface not to work as expected, and also create unknown problems for Solidify modifier.
I'm very new in Blender, I'm trying to make an old lock to improve my skill. I use "Subdivision surface" to mimic the round button and add "Bevel" to give its edge finish. It looks fine from outside, but inside the raised part it seems "Subdivision surface" can't find enough geometry. Its corner and edge doesn't look right. I may need to improve the topology according to other people's post, what should I change in the topology? I try to Bevel this part myself but it affects the Bevel modifier to round other parts.
(Subdivision surface create unwanted surface at inside corner, the edge gets bend to curve, and the shape of hole doesn't connect correctly. lack of clear geometry according to other people's post questions.)
Problem 2 - Unknown problem about Solidify result
Caused by Problem 1, I guess.
I add "Solidify" to make thickness, but as the picture show below, some strange thing is sticking out of my model. why this happen?