When blocking attacks it drains a lot more Stamina than intended often double my block cost listed on my Advanced Stats page - it appears that anything that reduces block cost is potentially not working such as Sturdy Gear or CP.
This is a huge issue for Tanks in difficult content - especially newer/inexperienced Tank who block more regularly as your Stamina is gone after using Pierce Armor and blocking a couple of hits.
This is only a small part of the issue.
The bigger problem appear to be when you block a hit you'll lose your regular amount of Stamina (Lets say 600 Stamina) and then when you drop block you lose the full cost of your block again (So about 1300 Stamina) so in total it can cost almost 2k Stamina to block 1 attack.
Current Block Issues:
1. You get charged nothing for blocking and when you drop block you lose all the Stamina you should have lost from blocking.
2. When you block 1 attack it ticks twice.
3. Block costs ignores your reductions such as Sturdy/Passives/CP and charges you the full amount.
4. Combinations of all of the above and probably more bugs.
We got confirmation this morning that a fix for the block cost issue reported in this thread will be going into the next PC/Mac and Stadia incremental patch (on June 14.)
As we only just fixed this internally for the upcoming PC incremental, it will not be fixed in time for console launch in a few hours. We're planning to include the fix in the first console incremental patch.