While we can add support for that, it was never meant to work before and isn’t the method Jon suggested using.
It’s also not a case of @showif not working with @ctx. It’s @showif not working with commands that generate a list of buttons. Hide blocks were how to hide those until now.
The next beta will have @toggle:update all for this purpose.
To use the evaluator for this, instead of multiple variables you'd just have one, and set it to different values. E.g. @set glob:Faves=1, @set glob:Faves=2, etc.
Then you test it like this: @showif:=$glob:Faves==1 etc.
Note the leading $ in the test; this is required when using the evaluator to access global variables.
When you use @set to set strings it doesn't need the quotes around it (@set is a legacy thing from before the evaluator existed). If you change it to @set glob:Favs=Server it will work.
You could also use the evaluator to set the value if you want it to be consistent: