I just upgraded to 1.5 with UBM and tried some mods after which weird things started to happen.
Basically, not only does my watchcrew fail to see anything but equally I cannot conduct attacks either, due to a very limited visual range or something. I was just about to hit a nice convoy but suddenly couldn't ID or lock scope even from a range of 1500m

There's like fog between us even though weather is absolutely clear. Noticed the same thing when leaving port. no watchcrew reports but didn't think much of it at the time.
What I did before was install/uninstall FOTRS (not my cup of tea, sorry) but it seems to have left behind some entries to recognintion manual anyway. Running mods now are
Ship Pack 1
Webster's Missing Voices
Natural Sinking Mechanics
Pacific Environment 4
Merchant Skinpack
Real Environment
Yes, I did all the install/uninstall stuff while at port and did it through JGSME. applying a mod at time and launching the game in-between installs.