I have a Marshall and I use snapshots religiously but I use my amp’s clean/dirty channels. As an example...
-I set snapshot 1 to FS2.
-I then set Ext Amp to the first INSTANT option in Command Center with (for me) Tip selected.
-I then set snapshot 2 to FS3.
-I then made sure the Tip option was selected for both snapshots (it will reset by default.)
Snapshots will reset the INSTANT blocks during snapshot setup. Once they are set for EACH snapshot then you will have them behave correctly, I think. Don’t set the Ext. Amp on FS switches if you intend to use the same switches for snapshots, then it’s a conflict of ideas and it will not work correctly.
If you haven’t, try that as a guide. Snapshots will flip all sorts of things on/off without having to put new blocks in, etc. However, for commands each FS button needs a separate command.