So the CMM5 is used for both PoE and GPS sync injection to connected PMP450 AP’s. The CMM5 is kind of a dumb device, so there’s not a whole lot of need to do anything with it. The GPS signal is used for consistency amongst sites and keeps the AP’s all running at the same pulse. In the first screen shot you’ve shown that “Cambium Sync” is being delivered, so that’s good! On the second screenshot, that shows the correct configuration for sync. I would not change the sync input to generate, as that would break the timing between the other AP’s and other sites.
Please take a look at this group of articles regarding the CMM5 and sync in general to get a better understanding of how this all works: