After refreshalts /ipplayer shows that last seen is set to 0.
But...days till deletion is not reset. That remains unchanged and keeps counting down.
A manual login does alter the days till deletion value.
So I think /refreshalts changes one value (last seen), but doesn't change the value that is used for checking when to delete chars.

Was the character that you reset online at the time?

No, he was not.

Right now I have my list with a colonel, a FDM, and 2 barons. They all should get the same amount of days till deletion, I would say.
2 of them have been seen last 2 days ago.
When I "/refreshalts all", the days until deletion don't change. The "days seen" are set to 0.

The "/refreshalts all" command does list that they have been changed.

I have 3 lcps, with days until deletion 25, 28 and 33, before and after /refreshalts.
Refreshalts with just 1 name doesn't make a difference.

Am I correct to assume that "days seen" + "days until deletion" should always be the same for the same exp groups, give or take 1 for rounding off?

It varies with experience, race and warlord rebirth.

Experience starts at zero (3 days) and goes up in increments until it maxes out at 1M exp (56 weeks).
Arch races like Seyans, Necros and Ninjas get the same period (56 weeks), regardless of experience.
Warlord rebirth get a longer period again (80 weeks), regardless of experience.

I think I see the problem.

See if that is fixed now.

The problem was in the original code but I did not notice when it was copied.
It was only checking login-date instead of the maximum of login-date and logout-date.

Looks great now.

I refreshed an alt that was seen 1 day ago and the time till deletion was raised by one.
All other values seem to match too.

I will keep an eye on it for a few more days, test a bit, but it looks like you fixed it

Created a new char, used /refreshalts as only means to keep him alive.
He made it past the 6 day deletion time for a private.
I would say the fix works 100%