If you get something similar to the above when joining through ArmA3Sync either to public or ops/training, then just uncheck battleye:
Alternatively you could select the arma3.exe when selecting the executable location, as the check option only alters that anyway.
Credit to Zurxo for bringing it to my attention, and helping out others earlier.
"Jokes on them, I was only pretending to be retarded."
"With the first link, the chain is forged. The first speech censured... the first thought forbidden... the first freedom denied – chains us all irrevocably."