Mask prevents player map load

[Bert Blaine]

I have a player, who when ever i have a map that has the mask applied, he can not load the map.
.....
this same palyer sometimes has issues seeing tokens on a map, and as such can not target them even in the combat tracker.
..................
he logs out and back in and that sometimes fixes the token issue but not the mask issue

[Leonal]

What our group does is to share all the maps with mask on to a second client on the GM-machine, then distribute the new campaign.dat file from the GM to the players who have map problems.