Rockstar has acknowledged a problem with rest mode on PlayStation 4 and GTA Online.
The latest update to the PS4 is messing with GTA Online, causing players to enter freemode on their own.
The system's rest mode allows users to suspend a game and power down, to later power back up and resume playing where they left off.
However, do this with GTA Online and you'll be placed in freemode solo when you boot back up. Trying to switch to another freemode doesn't solve the problem either.
Rockstar suggests closing the game entirely and relaunching it until it fixes the bug, although that pretty much defeats the purpose of the feature in the first place.