it seems the deployment screen has some trouble with ships that cost fractional points to deploy.
i just joined a large battle between several npc fleets, and had enough points to spend to deploy my flagship and a few destroyers. if i first select my two destroyers with 9.5 point deployment costs, i'm then able to select a third one that costs 9.0. but if i first select two 9.0 destroyers, or one 9.0 and one 9.5, i can't deploy a third one.
screenshots:
Spoiler
(http://i.imgur.com/RY4A6wk.jpg)
the ships are from the Blackrock Driveyards mod, and i've got a long list of other mods enabled, but i doubt any of those caused the issue.