The issue lately seems to be the polymer OEM trigger frame having a wandering or new spec. Lately I haven't seen any of the polymer frames function with the FFT trigger kit. You're hammer is definitely hanging on the disconnector shown in your photo. This is the exact issue I usually see and I've rebuilt around a 100 of these trigger packs.
You have three directions you can go to fix this;
1. Buy an A&S Engineering trigger frame. They copied the original OEM aluminum frame specs which allows these trigger kits to drop in.
2. Return the FFT trigger kit, and send your polymer OEM frame to Briley. They fit their parts to the OEM polymer trigger frame. This could also be done with the A&S Engineering frame.
3. Try to remove material from the FFT hammer seer. Not an ideal solution since you'd be removing surface hardened and NP3 plated material from the seer contact face.
Personally, I would go with the first option. You'll really like the A&S Engineering trigger frame. It will also count as another US made part.
https://ansshotguns.com/?product=enhanced-trigger-guard-benelli-m4