This is what users go on - The map sometime flashes onscreen & then disappears. Other times it never appears at all.
This is a symptom of too little memory being allocated to the VASSAL program.
Vassal 3.1 and later allow you to set the memory for a module using the preferences for that module. Open the preferences and increase the maximum amount of memory. This value should generally be lower than the maximum amount of RAM your system has installed.
For earlier versions: When using Web Start to launch VASSAL, it is allocated 256MB. When running the manual installer, you can select the amount of memory to allocate to VASSAL during installation.
There is no mention of what the JVM actually really means. Thus, big module, give it more RAM. Now that I understand what the JVM is, I’ve reduced JVM max heap to 512 MB. ATM everything appears to work when loading and playing a game.
Conversely, I have, in the past, received out of memory error messages, thus the steady increase to the JVM allocated RAM. Now, from memory only, the out of memory errors do appear to become more common when in edit mode.
I’ll monitor this situation and advise if any issues arise.