I changed the windowskin in RMXP for my game to a custom one, but it only shows up on the title screen, not ingame. Could this be because of the DubeAlex AMS I'm using or is it something else?
It is more likely than not that it is due to a custom script you are using.
You can try removing your custom scripts and putting them back one by one to find which script is the sinner.
Tell us your results
Remember to make backups ^_^
It likely is the AMS if you have not set these lines (around line 64):
@message_box_skin = "001-Blue01" #Choose the WindowSkin for the Message Box
@name_box_skin = "001-Blue01" #Choose the WindowSkin for the Name Box
Unless it also does not show the correct windowskin in other default scripts, like the menu. Doing what Zeriab suggested is a good way to figure it out.
thanks that worked