That's something CorneliousJD can't fix for you. It's an old AMP bug they even tell about on Discord. They normally would fix this for you in a second, but I guess you told 'em you're using the Docker application through Unraid.
Fix: Right click your instance > Browse Datastore > Edit the GenericModule.kvp > Change the matching 2 lines to those:
App.UpdateSource=Multi
App.UpdateSources=[{"UpdateStageName": "SteamCMD Download","UpdateSourcePlatform": "All", "UpdateSource": "SteamCMD", "UpdateSourceData": "896660"}]
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But I also got a question to you guys. Any clue why my instances don't start anymore after rebooting? I would guess it's something about the mac address parameter, but it doesn't matter if I use it or not, the instances won't start. They say they're started but turn offline as soon as I wanna manage 'em.