Imported stills get sticky - only one showing

I'm having a strange issue with stills I've imported for reference (screengrabs etc).

They appear to import as normal, and if I go to show Show Reference Wipe the still shows as normal, but clicking on any other still just shows the first one I clicked on. I can't choose the still I want to view. Switching the wipe on and off doesn't help and only the first still I clicked on shows.

Any stills grabbed within a project work as normal though, it's only imported stills that seem to do this. Sometimes it updates to the right still if I keep trying and jumping between stills, or by going to a still grabbed from the timeline and back to an imported one, but it's seemingly quite random.

The issue is the same regardless of format. I have also tried exporting the stills and reimporting the DPX files, but it does the same thing.

I have tried setting the gallery storage to a new location, and also manually emptying the .gallery folder. Currently it's stored on the system drive, but I have tried setting this to other external storage.

I have removed all PowerGrade and stills folders and started from scratch.

This issue has persisted for several versions, I'm sorry I can't actually say when it first started though.

Is there any other way to clean the gallery cache? It seems like some kind of database corruption.

Many thanks,
Paul

Resolve 14b7
macOS 10.12.5

Model Identifier: MacPro6,1
Processor Name: Quad-Core Intel Xeon E5
Processor Speed: 3.7 GHz
Memory: 64 GB
GPU: D500