How many Bibles do you have installed?
One issue that can arise is if two Bibles have the same tab name. e-Sword loads one and ignores the other, with no notification that there's a problem.
Another issue is e-Sword alphabetizes tabs in an unexpected way. After removing or installing resources, I've found it difficult to re-learn where specific resources are. Maybe this is happening in your case.
The reason is the tabs are not alphabetized from left to right, starting on the first row. Instead, tabs are alphabetized starting on the left side of the last row. And then moves upwards, with each row's sorting restarting on the left.
I've had a number of users tell me they've "lost" resources when it's just the resources aren't sorted like they would have thought.