GetPromotionDetails_API returns exception for some of the promotions:
Communication Failure: DataPacket type mismatch. Index X, Type 42.
The issue is caused by the bug with id #PBA-83482("GetPromotionDetails_API fails in case of many promo codes"). It happens when the promotion is of type "Promotion by One-Time Promo Codes" and has many promocodes attached.
The bug is to be fixed in one of the next OSA releases.