Threads and posts not being selected

[XYZ500]

I am trying to select threads and posts to mark them and then choose an option from 'moderation tools'. But when I click on that tiny box to mark the thread or post, it gets ticked but doesn't get highlighted (to show its been marked) and neither does the moderation tools show that any threads or posts have been selected and it keeps showing "Moderation Tools (0)".

I don't know how this happened.

Now I am not being able to delete any thread or post because its not being selected.

vB version: 4.2.3

See this: http://prntscr.com/aswn4l
4 threads have been selected. But moderation tools still show that no threads are selected and I can't take any action on the threads I selected.


How to fix it?