Trouble with manual sleep entries

Should I provide some more informations? 

You wrote:

Log_ said:

I do not sleep with watch

and then:

Log_ said:

Watch was recognise when I going to sleep and when I wake up.

The watch cannot recognize when you sleep, if you do not wear it.

Set up you bed time wide enough, so that you do not need to change it permanently (with a sufficiently wide margin), and wear the watch when you sleep, assuring that it reads your HR correctly.

... and when you want to edit the sleep time manually, do not do it on the watch, but rather in Garmin Connect. For example in GC Web like shown here:

Yes, I know what I said. If you don't sleep with watch device recognise when you take it down and when you wear it again. It saves it as sleep time. 

Ah, ok, I understand now. Never heard about that feature, and not sure whether it was intentional or accidental behavior.

Im sure it is (or it was) a feature as it was working about two years as I recall. 

I check my GC app and it stopped working 02/19.

You could try installing the firmware version you had at that time, to see whether it helps. And report it to Garmin Support, if you find the feature indeed stopped to work due to a newer firmware.

Where from I can download old firmware? Links from posts are not valid any more. 

Log_ said:

Links from posts are not valid any more. 

Not sure what version you are looking for, but for example the zip file with the beta version 16.91 that contains also the fallback public release v16.50 is still available in the thread https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/instinct-solar/288781/instinct-solar---16-91-public-beta. For older versions, check other, older threads with beta versions (they always contain also the last public release firmware as a fallback option), or ask other forum members - perhaps someone kept the file.