I'm on PC EU and I've noticed having issues weaving LA's, people in my group noticed it as well and many raid groups reported it as well.
The bugs effects LA's sets really heavily like relequen and advancing yokeda and in general it's a dps loss missing them.
We have a nb in our group, and missing LA's on a nb is basically a death sentence after zos repeatedly killed the class every patch now their LA's don't register at times.
How to replicate? Not sure but I think you need to have really high cpm.
Cause for this bug? It's speculation at this point but I'm pretty sure it's somehow related to the 7 meter la range for everyone I think something messed up.
I would urge the ZOS devs to have a look at la weaving, sometimes doing a simple click locks you into a HA animation for some odd reason.