I disabled all add-ons
I made sure no other key is bound to my binding (shift-E)
I tried changing the Action bar lock to every other option
I tried changing every option in self cast options
This is actually just down to logic. If you have something with zero conditions before something which has conditions, the second spell will never actually be actioned because the first always supersedes it.
Ráevelyn’s first solution works because they stipulated conditions on the first spell as well. The second solutions also works because the order is changed and the conditional spell comes before the open spell.