I have a lot of saved presets on my VFX for commonly-used settings.
Just tried my "Brightness and Contrast" presets in V21 (brought over from V20)... when I select most of my custom-saved presets (created in V20 or earlier), the sliders do not adjust to have the correct values! Effectively, most of my custom presets no longer work. Some do, as do the first few (system default presets). It isn't that the FX does not work -- it's that when choosing the custom saved presets, none of the controls move.
Here's a quick video demonstrating (3 minutes.. but you can get the idea earlier on)
Although it seems this is isolated (currently) to Brightness and Contrast... I fear I'll find this with other FX the more I work with it.