Vacations keep disappearing

Hello,
I think I found a bug with the Vacations feature.
When you have vacations set and you then go in setting page and save settings there, sometimes it removes all the vacations that were set. No warning no nothing. All removed.
It sometimes even deletes them even you enter fresh in that setting page, meaning you loaded vacations data in that page. Sometimes it keeps them – I think it kinda deletes them if there it passes more than one minute since last save in settings page.