I'd like to share a comment from User Interface Lead Minagawa explaining the reason that target lock isn't functioning while the cross hotbar is active.

Quote Originally Posted by Hiroshi_Minagawa View Post
Greetings, everyone. User Interface Lead Minagawa here.

The reason why Target Lock isn't working while the cross hotbar is active is because we assigned a new control feature called "Duty Action" to the L3/R3 button.

We apologize for taking time to update you on this.

This is working as intended and not a bug. However, since it was a change made to the feature, it was something that should have been announced in the Patch Notes but was missed. When we were creating the patch notes, we were addressing an issue with the Duty Action with the L3/R3 button, which caused it to not make it into the notes.

Would it be possible to make it so you can still lock on a target while the cross hotbar is active?

We're currently looking into this with the programmers, but we're having trouble getting the new control and old control working at the same time. We're looking to see if it's possible to revert the controls to the older method when the Duty Action is not available. However, since we have various control options available on the hotbar the system is pretty complex, therefore it is difficult to add a process which checks for this condition. For this reason, we're sorry but won't be able to fix this issue quickly.

We continue to work with our teams to look into other methods, such as making it so that the Duty Action can be registered onto the hotbar and add an option to revert back to the previous L3/R3 behavior to resolve this issue.