always save before a mission ends. Then if that comes up. Exit xcom boot it up again and load the save, then complete them mission again in 10 seconds and it will most likely be fixed

mod list? usually this is a result of a mod conflict with long war 2

http://www.pavonisinteractive.com/phpBB3/viewtopic.php?f=19&t=23455&hilit=underneath&sid=b54630012b7f82f1eeb82c739778e03f

This is most likely caused by one of your mods. List your mods here and we can help

Also if you only have 8 GB of memory when the game takes up 6+. For me I had to remove a couple of mods that were not working as advertised. 'Facility Hunt' and 'Chain Lightning'. You may have to start new games for them to work. But you have very few mods.

thanks all, really helpful apreachiated it, i still had outfit mod . seems like that has solved problem. Link helped massively.

It's definitely not a machine's memory cap issue. My rig has 64GB of memory and XCom has peaked at just over 4, yet I still get this bug. I think it may be some sort of memory allocation issue, where XCom allocates 4GB programmatically then hits that cap. Fewer mods mean less likely to hit that cap also.

A restart of XCom has consistently "solved" the issue for me.

Most people managed to identify a single mod that caused this. If you post your mods here, we might be able to help