Expectation is that wall of putrid flesh removes the cool down if it isn't destroyed during it's use.

It keeps the cooldown despite surviving the encounter.

This was working until I first gathered my poltergiest.

*snip helpful info ty for adding so much*

Some necromancers were abusing a bug to clear the wall of flesh cooldown.

That won't happen anymore. The cooldown remains.

Why would wall of putrid flesh lose its cooldown?

Wall of Putrid Flesh has been changed recently either unwittingly
or covertly as I cannot see any official code change announcement
for it.

It used to clear the cooldown if the wall retracted by its own
accord. It used to keep the cooldown if the wall died in combat.
This was the way it was designed and the way it has worked since
it was introduced as a spell.

Now the cooldown remains even if the wall retracts by itself:

For example:
An animated wall of putrid flesh tumbles to the ground, seeping back to its grim origins.

It looks like, though, that the bug me that the cooldown EVER disappeared.

I'll dig more into it and if that is the case, remove the situations that resulted in a cleared cooldown. Or if the opposite is the case, adjust the cooldown clearing to be consistent.