Error in RPT:
18:54:13 Flushing file C:\Users\New\AppData\Local\Arma 3\MPMissionsCache\__cur_mp.pbo not possible - still open
Currently the fix I have been doing is, restarting Arma & everythings works like normal.
This is a minor bug since the first 1.54 update, though I thought I'll post this up to help report any issues to improve this great game.