Images disappeared from the phpbb gallery, version 3.0.x, how to return?

Question

phpBB

Good day!

There is a forum on phpbb, version 3.0.x. Recently, images in the gallery have ceased to be displayed there, while if you open a page with an image, everything is fine. In the gallery it looks like this:



Nothing has been changed, nothing has been touched. We need to update the version, but for this we need to redo the style for the new one, and there is no time for that now. Is it possible to fix this jamb without updating? In which direction to dig, where to look for the answer? Tell me please.