HEIC files opening externally in windows after v1.0.0 update

[Zekuma]

WIndows 10 latest updates, x64

After installing XnViewMP 1.0.0 opening up a thumbnail of a new HEIC file from phone results in it opening in the windows Photo app and not within a tab inside XnViewMP.

I do not know if windows has updates Heic drivers behind the scenes and grabbed it, but after this issue many versions prior, it has always been internal.

I have reinstalled XNViewMP as that should refresh the HEIC driver but still opening in external today.

Any ideas?

[Zekuma]

Further:
Reinstalled XNViewMP, remembered to run as Admin the first opening.

Restored most HEIC files opening internally from thumbnail.

Some still randomly don't. XnViewMP triggers a download of photo file from OneDrive. On some photos (slow download? processing error, metadata error? speculation) it will still open external windows Photo.

If I copy the affected photo to another folder and then let XnViewMP see it, make a thumbnail, and then click to open, it opens normally inside XNViewMP.

[xnview]

try "View>Update catalog from files"

[Zekuma]

Regrettably, no, not a success.

It is curious behaviour, at least the workaround of copy paste to a new directory solves it now for the edits I wish to do, but why it does it to some files and not others I have no ideas. Probably Windows...