Game Version 2.0.1e
The interaction between Armour Training and Tower Shield Training, as well as Tower Shield Defense, appears to be bugged for Tower Shield Specialist, which would render the class obsolete. Depending on your interpretation of Tower Shield Training, the dexterity bonus for a level 11 TSS (pictured) with 30 dex wearing banded mail and wielding a tower shield should be:
banded mail: +1
armour training: +3
tower shield training: +6 or +8
= +10 / +12
As you will see, however, the dexterity bonus remains at +4 (banded mail + armour training). In an odd twist, removing one’s armour whilst retaining the tower shield actually effects the latter’s +2 dexterity bonus, but not the incremental bonuses purported to be added by the Tower Shield Training feat. Lastly, the Tower Shield Defense feat appears to do absolutely nothing whatsoever, although the aforementioned dexterity bonus from the tower shield is added to touch ac if the armour is removed.
I have read numerous posts on similar issues with armour training, but in fact armour training appears to be working as intended. It is Tower Shield Training and Tower Shield Defense that are not. It may have something to do with the update in 2.0.0z (pictured)?
Note: this is a brand new character with no strength or fatigue issues and no history of such issues. It has been reloaded into the game multiple times and zoned in and out of various areas. I am noting this because it was a fix for others with an issue with armour training. This is not the same issue.