Map updates still occur but on a much lower frequency than the stock game and IIRC only within a smaller defined radius. They have not been disabled, just reduced.
Within GWX, you can hear further than you can see and if you man the hydrophone, further than your crew can.
As to increasing the map report frequency, not an easy fix I'm afraid. I involves opening the Campaign Editor and adjusting the report frequency and distance for nearly every ship, convoy or taskforce in the GWX campaign files. There used to be a mod called "Spy Cam" which did this for you but I do not know if it was revised for the last GWX release and it was a huge overkill. It showed real time streaming traffic.
I suggest you camp out near high traffic areas and use the hydrophone. Early war is north of Ireland/Liverpool convoy route or south Ireland/Bristol route.
The last Spy Cam mod I had any involvement in was for GWX 1.03 and it did this:
