I have this problem too,nothing shows in decks,cannons,beams or pirates...! it does say if there is room for anything ie room for cannons 0/6 but i could not see them to interact with...!
This was a problem as i needed to add some pearl cannons but could not see the 30 pounders i wanted to remove first....
I was advised to change my browser by the mod who looked at it as he couldnt see the problem.
I didnt do this instead i sold all the 30 pounders moved the p.cannons on deck then bought new 30 pounders to make up the numbers.....lol
HOWEVER i have since noticed that if i scroll down in the trove all the info i was looking for seems to appear in the left colum(ship)
I have no idea why this is and its something ive just put up with...! lol
Try to do the same i would be interested to see if this is the same for anyone else?
I use mozilla firefox
I hope this info may be of use!