Legendary Raid Glitch question

If the raid clock has expired, you can't get back in. Otherwise it may work, but I'd never say "without any problems". The whole raid process is pretty glitchy, almost anything can happen. Especially if your signal strength is weak.

Last raid my app froze while I was in the lobby. I restarted and re-entered the battle as it was ending, still got a chance to toss balls and watch Lugia flee. I also got a TM and 13K XP, so much better than nothing at all.

today during a raid me and another guy when fighting lugia its health bar stayed the same. When the others koed it we reset out games and went back to the gym and we were able to still catch it but I havent tried leaving during the raid.

I tried to rejoin the battle with 6 new pokemon, it was the same time as it was defeated, error out, no chance to catch...

You can't come back if the raid is over either by time or KO, so you need to time you team change to avoid this situation, even if you have to "quit" while some Pokémon are still good to go.