Strange unexplained behaviour

[simato73]

I have found some behaviour today that I never saw before and while I have identified when it is triggered, I cannot explain it.

I have edited some tiff images in Photoshop using Nik filters and saved as multilayered tiffs. The images have been opened in PS from PSu.
After saving and verifying the folder, when one of these images is highlighted and I press either the Preview button or use Shift + Enter, instead of entering preview mode an external program, Lightzone, starts instead. No idea why Lightzone, of all programs.
I am totally baffled why this happens, and also a bit annoyed.
This happens also when I use the Adjust button.

If I select any other image (Jpg, raw or even tiff, as long as it has not been edited as described above) PSU behaves normally.
So there is a workaround to avoid the observed behaviour - just do not select the offending images before selecting Adjust or Preview - although this is not ideal.

Has anyone seen something similar, is it a known issue?

[Hert]

PSU will open TIF locally. Is your extension TIF or TIFF?
Also make sure that you don't have the TIF or TIFF extension added in Preferences-File Handling as a non image format.

[simato73]

PSU will open TIF locally. Is your extension TIF or TIFF?
Also make sure that you don't have the TIF or TIFF extension added in Preferences-File Handling as a non image format.

The file termination is .tif with one f only.
I am not sure what you mean in the second line of your reply.
In the Preferences-File Handling-Other File Extensions I don't see .tif or .tiff if this is what you mean. I see only what seem to be video format terminations.