brand new to blender here. Recently started following some tutorials to learn how to sculpt and model in blender. After one video, I decided to run off on my own and try to mess around a bit. Ran in to an issue where after a bit of preliminary framing and stretching of my shape, I can't edit it with any of the "add material brushes" (draw, clay strips, inflate, etc.) but I can still "transform" it (snake hook, grab, etc.). I think it has something to do with dyntopo and the circumstances surrounding my usage of it, but I'm not too sure. This has happened twice now and I can't seem to find any option to change within blender nor any similar question online. Any help is appreciated here!
I ran into a very similar issue. I'm using version 2.91.2 on Windows. Only Grab, Hook and Clay appeared to work for me.
To fix it, I started off by trying everything in this Blender StackExchange answer - Sculpt tool not working - But it didn't help.
Restarting Blender however, did the trick.
I would have answered on question I linked to, which is much easier to find in a Google search, but community rules prevented me from doing so. So happy days if you find this answer, and it works for you.
Also check your brush tablet pressure settings, just in case:
You'll want to switch them off, when troubleshooting issues with sculpt tools.