The filmstrip loses focus - Del isn't working

I can understand your frustration if this worked before but there is another way to do what you want. It works slightly differently but end up with the same result.

As you come across an image which you'd normally delete, hit the X key instead to mark it as "Rejected" then once you have finished going through your film strip go to the Photo menu and at the bottom is "Delete Rejected Photos" which will get rid of them all in one go. I think it might be slightly quicker than your current method.

Hope that helps

Josef,
I have noticed something similar which may be related. I can select Develop and make a couple of simple changes (such as Crop,Auto,White clipping) to the image, press the right arrow to move to the next image, press Previous to replicate the changes, make similar basic adjustments, press right arrow to move to the next image etc.
I have found that every 7 or 8 images, the right arrow does not work and I have to click on the screen to one side of the image (to re-focus) and then everything is OK again for another few images.
Now I know this does not entail restarting LR and it does not help you BUT it is an 'idiosyncrasy' that is similar and may have the same cause.
I use LR Classic 8.1 and Windows 10.

Hi Jozsef and Michael,

I am not able to reproduce this issue. Can you share a screen recording when you encounter the issue. That will be really helpful.

Regards,
Chinoy