Firesong broke a lot of stuff when it comes to blocking:
-block doesn't persist through dodge roll, you have to click right mouse button again
-block sometimes drops if you're using a key combination (for example hold right mouse button + click left mouse button) to bash, works fine if you're using a single button to bash
-trying to cancel a channeled ability by clicking block will stop the channel but won't block any attacks, in order to make it work like it did before you have to quickly press block twice
-even if you're using a single button to bash, you might still drop block if you're trying to cast a skill at the same time
-similar to dodge roll bug and channel bug, if you're holding block and get staggered like for example in Sunspire, your block won't come back up on its own like it normally would, you have to click right mouse button again to reapply it
Here's a video showing first three of those:
https://www.youtube.com/watch?v=Q6sMEVGhyeU
Since there have already been 2 additional maintenances and no mention from ZOS about them being aware of this issue, I'm beginning to wonder if they know this is a thing.
@ZOS_Kevin can we get more information about it? Are the devs aware of it?