2 weeks in a row after the Barron Geddon fight my imp was unable to phase shift. I became the bomb in both weeks and believe it has something to do with that.
I reloaded ui, dismissed and resummoned my imp, and tried using the spell from macro commands instead of auto or clicking the spell.
This is quite a nuisance because for the rest of the run my imp will get killed over and over and my group and I lose blood pact.