It is no secret I do not like the new style chain damper because it fits lines up poorly on the chain, but it doesn't usually cause a direct fitment issue. There are two options for the damper, chamfered and countersunk bolts. I would bet the bolt is hitting the cover
Rock Auto shows 2 different designs, one is for a chamfered hole, one for a counterbored hole 1988 BUICK REATTA 3.8L 231cid V6 Timing Chain Guide / Damper | RockAuto