I don't know if anyone else noticed, but the MK XII Dominion set does not recognized ANY shield regeneration. I tested this by taking off my Borg MK XII set and putting on my Dominion set, and the regeneration numbers disappear when the dominion shields are equipped. The regeneration for my Borg set is 583/3 seconds.
Borg shields sometimes have that issue. The only really bug free shields are the standard shield types (regular, Covariant, Resilient, Regenerative). A lot of the set shields have UI display issues atm it seems.