Issue selecting multiple files to import

Since upgrading to 15.x I have an issue when importing images, where when trying to highlight a series of images using Shift+Left Click the highlight won't stick, it just flashes and leaves the first selected image highlighted. I have to wait around 30 seconds before the highlight sticks and I can tick the images for importing. I don't know what the app is trying to do at this time, but this didn't occur in 14.x and whilst doesn't seem like a major issue it still has an impact on my work flow. 

Steps:

Click Import

Click Untick All

Select first image I want to import

Select last image (holding shift) in the series I want to import 

Highlight won't stick

Wait 30 seconds

Select last image (holding shift) in the series I want to import 

Highlight sticks

Press spacebar to tick

Click Import

HURRAH!

Once it's finished with this silliness, I can open Import and it'll be responsive as normal. If I eject the SD card and re-insert it'll do the same 30 seconds of it doing 'something' where I can't select multiple files. On top of the denoise debarcle LrC is becoming a really unfriendly user experience.