I fought Vortex 4 for about 4 hours testing my team.
My attack debuffers were at 260ish Accuracy. The boss has 260 resistance. It went great, I can't even remember how many times I died to a failed debuff because it was that rare. Easy 6 minutes tests.
I farmed some gear, upped my accuracy to 300-310 just because I could, and now I miss about as much as I succeed on my debuffs and for the past 3 hours I haven't been able to reach 6 minutes.
Now I have to go and reduce my accuracy just so that they will stop missing the debuffs.
Please have this truly fixed. If the issue is that there is a soft cap and the soft cap triggers some kind of negative effect instead of just reduce increases then make those stat ranges clear to us instead of us having to find out the hard way.