I had the same issue with the DVA1622's loader after updating to v9.1.0-10660 through Package Manager, and I solved it by downgrading Surveillance Station to v9.0.2-10061 on all my servers/installations (an old DS214se, a newer DS220+ and two xpenology NVRs, managed by CMS inside VirtualDSM on another server). No need to change SN (for now).