You haven't given us a ton of information, but I think the main issue here is that you're missusing the double-pipe (another way to perfom a boolean "or") operator.
In general, your formula syntax is pretty wrong (using IF() without specifying 3 parameters, the IF() is probably unnecessary, using 2 separate OR operators with both usages being ...
So the issue was in the template.
I had included slds css in the template.
For some reason it was causing issues in time-based workflows but works fine in immediate ones. After removing it, I received the email.