support answered said try to drag the camera to the center screen from the left, then drag it back to where it was in the dropdown on the left for the cameras, that worked, the calendar came up.
Make sure the calendar button is blue. If you click on the calendar button it shades to gray, so make sure it is blue before dragging a camera to the center and dragging the center back to the camera area
What a pain but for now this may work for you also

Here is a link to 8.8.5 if that helps to roll your version back
https://home-cdn.reolink.us/files/client/electron-release/reolink_setup_8.8.5.exe

I upgraded to 8.10.4 and on playback I can not get the calendar to pop up to change the date of playback.
Any suggestions?
UPDATED:
I had to install the earlier version support was great but we just couldn't get the new version to run right.
Here is version 8.8.5
https://home-cdn.reolink.us/files/client/electron-release/reolink_setup_8.8.5.exe

@joseph_1979 Thanks might have to reinstall and try. I don't really like the software to begin with but it is what my customer bought.

@user_694180074676378_694180074676378 Can you tell me which version of Microsoft Visual C++ Redistributable package you have? If not then install this https://aka.ms/vs/17/release/vc_redist.x86.exe and re-run Reolink client again.

I was not sure where to look for it and installed the one you mentioned and it still did not pop up the calendar. For not I will have to do like support suggested and to drag the camera from the left to the center and drag the center back to the camera selected to the left again. But the calendar button needs to be blue to display the calendar when dragging back and forth.

Here is a link to 8.8.5 if that helps to roll your version back
https://home-cdn.reolink.us/files/client/electron-release/reolink_setup_8.8.5.exe

Support gave a link to older version I tried all their suggestions and even though the calendar worked after dragging a camera to the center then drag the center back to where the camera was, I found after doing that the live view did not display then. So back to 8.8.5 version.
Here is the link if you are also unsuccessful with 8.10.4
https://home-cdn.reolink.us/files/client/electron-release/reolink_setup_8.8.5.exe

@user_694180074676378_694180074676378 Can you tell me which version of Microsoft Visual C++ Redistributable package you have? If not then install this https://aka.ms/vs/17/release/vc_redist.x86.exe and re-run Reolink client again.

I was not sure where to look for it and installed the one you mentioned and it still did not pop up the calendar. For not I will have to do like support suggested and to drag the camera from the left to the center and drag the center back to the camera selected to the left again. But the calendar button needs to be blue to display the calendar when dragging back and forth.

support answered said try to drag the camera to the center screen from the left, then drag it back to where it was in the dropdown on the left for the cameras, that worked, the calendar came up.
Make sure the calendar button is blue. If you click on the calendar button it shades to gray, so make sure it is blue before dragging a camera to the center and dragging the center back to the camera area
What a pain but for now this may work for you also

I reinstalled and still no luck getting the calendar to pop up on playback to change the date. Installed Java and still nothing. Ran as administrator still nothing.
Very frustrated and may need to install the earlier version.
But can not find the earlier version on Reolink site.

Ich habe das gleiche Problem mit der Version 8.10.4 neu Installieren und ausführen als Administrator löst das Problem leider nicht.

Thanks will see what happens when I try to install again

@joseph_1979 Thanks might have to reinstall and try. I don't really like the software to begin with but it is what my customer bought.

I upgraded to 8.10.4 and on playback I can not get the calendar to pop up to change the date of playback.
Any suggestions?
UPDATED:
I had to install the earlier version support was great but we just couldn't get the new version to run right.
Here is version 8.8.5
https://home-cdn.reolink.us/files/client/electron-release/reolink_setup_8.8.5.exe