The Felchlin cocoa butter that I have does require being melted down completely and fully hardened overnight at room temperature in a clean container before putting it in the EZtemper. I've found that happens with any cocoa butter that is old or hasn't been stored well.
I took a lumpy canister up to Guelph 2 weeks ago and the grad student of my favourite fat chemist tested it for me. The lumps are form VI!