Ouch, that's unfortunate :(. Sorry about that!
I did a quick test and couldn't get the result you describe - my magic/reaping attack captures the Zealot as intended. Could the attack damage have been increased somehow, for example by a multiplier, a chain bonus or an equipped Blood Cloak? Did it happen in the Frozen Horror scenario or in Chaos Realm?
I'm working on the next patch and will definitely fix this bug if I can replicate it. Thanks a lot for playing and reporting!