This is intended - that time is only updated every 15 minutes to keep things fast on the server side:
The rationale is that this number is tracked to give folks a rough idea of whether a given user is still active; the primary implementation concern is raw speed, not accuracy.
What can cause a question to be bumped?
What can cause a question to be "bumped" to the first page in the Active tab of a Stack Exchange site? (Changing the "Last Active" date.)
The following activities will cause a question to be bumped:
Addition of an answer
Editing the question or any of its answers (even if the answer is deleted) * † ...
As Deltik said, this was a side-effect of the database migration that happened earlier today.
Should be fixed now. We just had to rebuild a few services that didn't get rebuilt after the migration took place.
Yes, this is due to the recent database migration. As far as I can see, all Stack Exchange sites are affected except for Stack Overflow, which was the first to come back to life.
Stack Overflow Meta was taken down to read-only mode momentarily, but when it resumed operations, like the other sites, it still did not show new activity.
The only thing we can ...