Master admin vs. profile admin for creating profiles - is there a difference?
Installation and Configuration
The only thing I can think of is that you never "viewed" the profile you created after you created it by the master admin.
If you remember in JR4, you had to go into artist - change artists and "select" the artist you wanted to be your active artist. We've done away with that in JR5 so whatever profile you are viewing (when logged in as an admin or master user) is your "active" profile.
The profile tweaks module has a check in it to only show modules that are allowed in the quota of the active profile. So if you never view a profile as the master, but just go directly to modify their user account and then click on the "customize" tab, you're going to still be set at whatever was the last profile you viewed.
So if you first make sure and view the profile, then click on the "modify" for that profile in the profile header, it should work.
I think there might be a way to improve this a little bit by double checking in the actual profile tweaks form, so I will check that out.
Hope this helps!