Can't search multiple photos by filename

Hi there, 

I'm coming in with a very frustrating issues in Lightroom CC I didn't have in Lightroom classic nor in Capture one, which should be pretty simple in my opinion : searching for multiple photos by filename(s) 

Not only I always get a blackhole, but even searching for a single file name doesn't work. ( Even if I'm copy / pasting the exacte file name from the actual file. 

Also when using a service like Pixieset.com for your client to review a gallery, I know you can copy a client's selection and paste it into Lightroom Classic or Capture One to get the same selection easily. Why isn't that working on Lightroom CC ?! 

If anyone can provide any help with this issue, I would truly appreciate it because it's been very frustrating and slowing down considerably my workflow. 

Best, 

Chaz