I have the same issue.
Bots and vehicles spawn, start moving, and then all disappear... only bots are left without vehicles.
Then it tries to restart event again in different location and goes in circles creating bots around the map.
Can't end event with convoystop - I need to kill/unload the plugin
For me this happens only for nightmare_reforged preset. If I test with the old one - hard - then all works fine.
Screen attached
RCON is spammed with these kind of messages when the issue happens
09/30 13:34:57 | dynamicpreventbuilding[92662525] changed its network group to null
09/30 13:35:00 | dynamicpreventbuilding[92662618] changed its network group to null
09/30 13:35:02 | NullReferenceException: Object reference not set to an instance of an object
09/30 13:35:09 | dynamicpreventbuilding[92662992] changed its network group to null
09/30 13:35:12 | dynamicpreventbuilding[92663068] changed its network group to null
09/30 13:35:28 | dynamicpreventbuilding[92663567] changed its network group to null
09/30 13:35:31 | dynamicpreventbuilding[92663682] changed its network group to null
09/30 13:35:39 | dynamicpreventbuilding[92664674] changed its network group to null
09/30 13:35:42 | dynamicpreventbuilding[92664756] changed its network group to null
09/30 13:35:57 | dynamicpreventbuilding[92665247] changed its network group to null
09/30 13:36:00 | dynamicpreventbuilding[92665335] changed its network group to null
09/30 13:36:09 | dynamicpreventbuilding[92665723] changed its network group to null
09/30 13:36:12 | dynamicpreventbuilding[92665816] changed its network group to null