@tzervo
Greetings Captain,
as the first steps, please try:
1) Verify integrity of game files in Steam (right click on Naval Action in Steam, click on properties->local files)
2) https://forum.game-labs.net/topic/19975-workaround-for-certain-ui-loading-problems-inlcuding-trader-tool/
3) https://forum.game-labs.net/topic/19975-workaround-for-certain-ui-loading-problems-inlcuding-trader-tool/?do=findComment&comment=542624