FSlogix failes to attach vhd - intermittent issue

Hello,

we're currently testing our to-be new Horizonn environment and are using FSlogix for the profile handling. It all works fine for most users who are testing it.
However, some of the users randomly get a 'failed to attach' message (attached). I searched for the status, reason and error codes, but no luck.
Also, when this happens, if the user just keeps trying and reconnecting to the VM, it will start working after an x-amount of tries (usually 3-5).

I'm at a loss as to what causes this.

Thanks!