When your MH was wired, the person screwed up and reversed the wire connections going to the one side of your MH lights and it may be easy or hard to find or get at where the screw up occurred as it may be behind a wall or ceiling panel. If you use a VOM etc meter, you may be able to find where it occured and be able to correct it quite easily, unless it's hidden.
Not the first time by far an owner has found this issue in RV's and sure won't be the last. LED's are quite new on the scene in the RV industry and before them, light bulb current flow polarity wasn't that critical for only incandescent bulb use but was certainly against RVIA and commonsense rules and acceptance. Some of the workers in the RV industry are not well enough educated to know the difference as they are often entry level employees and this is their first experience with this type of work. A shame as RV's are not cheap throw aways. Inncorrect wiring is and can be a serious fatal fire hazzard anytime and it must be corrected ASAP.