I made a test map so I could test scale effects on underwater provinces. To ensure that I had the same start loc I modified a test version of Glory of the Gods Multiplayer to have only 1 start location underwater.
I chose Shipwreck Shoals (249)
#landname 249 "Shipwreck Shoals"
#terrain 249 6
Whenever I start in that province with a dormat/imprisoned pretender on turn two all scales go to neutral.
This happens every time I create a new game with this setup; on turn 1 scales are as per dominion. Turn 2 they are 0.
This does not happen in any other surrounding provinces.
I can't see anything special in the map file regarding that province.
Seems very odd to me.