There are 3 parameters in core config ( and their default values )
corpseLimit = 15;
corpseRemovalMinTime = 10;
corpseRemovalMaxTime = 3600;

Explanation
if <=15 corpses, corpses are removed after 3600s ( each corpse should have its own timeout)
if >15 corpses, the corpses will be removed after 10s, starting from the first corpse

You can edit those parameters by adding them to the Desription.ext

Example
corpseLimit = 1;
corpseRemovalMinTime = 30;
corpseRemovalMaxTime = 120;

Please let me know if this explanation is clear to you , try to repro this issue using these parameters and let me know. Thank you

never mind, didnt read properly

Thank you for the explanation. I was completely unaware about built-in corpse removal feature, now I've googled it and turns out it was only ever mentioned once on BI Forums, probably unknowingly copied from official mission. The only thing that still bothers me is that we've clearly had AI corpses right next to player corpses and none of AI corpses disappear by themselves yet player corpses were gone in few seconds after death. Thank you, I'll try to perform tests with these parameters and let you know if it fixed the problem.

I have a question

Explanation
if <15 corpses, corpses are removed after 3600s ( each corpse should have its own timeout)
if >15 corpses, the corpses will be removed after 10s, starting from the first corpse

One of the above has to be either <= or >=, which one? Sorry for asking this but, this is not clear at all.

also what happens if corpse limit is 0?

its <=15 corpses are removed after 3600s ( each corpse should have its own timeout). Sorry my bad, Ive corrected my first post.

With corpseLimit = 0 corpses start to disappear after corpseRemovalMinTime

Thank you!

I did tests with following settings in description.ext:

corpseLimit = 1;
corpseRemovalMinTime = 1;

Second corpse always got deleted right away after player control switched to respawned unit. In other words, problem is solved and ticket can be closed. Thanks a lot for the help, this "bug" been bothering us for long time.

resolved, not a bug. Just a clarification of a function + parameters .
Closing