Er, well there's still a tank bug in mids, but it's slightly different than I originally thought. Apparently toggling on the first tank attack for stats in mids is now applying the -20% resist debuff that it deals to opponents to your mids stats.
I was testing the proc in the first attack of a bunch of attack sets, and slotting the proc into them allows them to be toggled on which screws up the display. Also the main tank build I'm looking at is titan weapons, which can have the first attack toggled on for the display anyway (since it has a defense bonus).
So, the proc isn't bugged in mids, but the first tank attack is now.
Well, at least it's easy to work around this now. Toggle off defensive sweep (or whatever your first attack is, if you've slotted the ATO into it) and get the right resist numbers.
Culex's resistance guide
Incidentally you cant seem to "stack" the proc x3 in mids like you can with other stackable effects.
Jem - Ill/Rad Controller Lv 50+3 Nic - Mind/Psi Dominator Lv 50+3 Lady Liberation - Invuln/SS Tanker Lv 50+1 Invicitx - Demon/Pain Mastermind Lv 50+1 Celeste - Emp/Arch Defender Lv 50+1 Nightsilver - DB/WP Scrapper Lv 34 Dusk Howl - StJ/Regen Brute Lv 32 Kyriani - Time/Energy Defender Lv 41Psifire - FF/Psi Defender Lv 50
Star Lighter - LB/LA Peacebringer Lv 30
Warning to everyone who uses mids for tank builds:
If you slot the tank proc into the new version of mids it will act as if your tank's base resistances are -20% instead of 0%, throwing off all the resistance displays. It stays like this even after removing the proc from the build. I don't know how to fix this if the build is saved after doing this.
Culex's resistance guide