I use a lot of filters in Gmail, which apply various labels and sub-labels to incoming messages.  Normally when I log into Gmail, the labels and sub-labels are exactly as I left them the last time I was logged in, meaning that if Label 2 is a sub-label of Label 1 and Label 1 was expanded so that I could look at messages in Label 2, then Label 1 is still expanded and Label 2 is still immediately visible the next time I log in.I like this.What I don't like is that, for the last month or so, my labels have been collapsing on their own, about once per week, so that only the top-level labels are visible.  In other words, every once and a while the expansion of the labels is reset.  For me, this behaviour is abnormal.Why is this happening?  Should I be concerned?  Are there any recent changes in Gmail that explain this?  Has anyone else had this behaviour?It might only be happening for my mobile browser view, but I can't be certain until the next time that it happens.
Expanded sub-labels keep collapsing in Gmail
gmail;gmail labels