Note, I'm testing again on my MC Client Workstation.
For me, a view of image thumbnails, all I have to do is check the field and then deselect all files instead of selecting another file.
Do you leave the checkbox field "open" with the box still displayed? Because that would leave the tag in an unsaved state. If I do what you are doing, but using a TV Series display, then when I highlight the series again (without leaving the view, just clicking on another series after checking the box), the checkbox is still "open" in edit mode. Clicking on the tag name in the tag window closes the edit mode and saves the value "1" in to the field, which is what is displayed in the tag value field.
Perhaps clicking anywhere away from the checkbox tag field should save the value and close the field for edit. It definitely isn't doing that at the moment.
Then it will be unchecked when I select the file again.
I have the Checkbox field visible as a column in my view. When I click on the Checkbox at the Series level, with the files list open below, checking the box takes a deliberate click. I have been able to confuse it a bit by checking and unchecking the box a lot, so that sometimes it takes longer to get the check to stick, but usually it works first go. However, the tick mark isn't always immediately displayed, and sometimes not until I move the mouse over it, both at the series level and the file level. So there is some delay in the field value display update.
Usually, however, it updates in the tag window pretty much immediately, and when it does the checkboxes at the series and file level in the view update immediately. I thought maybe you were double clicking the field, so checking and then unchecking, but that seems unlikely.
If clicking the tag name to close the checkbox field for edit doesn't make the check stick, what happens if you click the checkbox, then press enter to uncheck it, and then press enter to recheck it, and then click the tag name? Did that make it stick?
And then a can of worms fell open . . . On a different, but possibly related issue, and another form of weirdness observed while testing.
I know the space bar is interpreted as Pause/Play, but while testing if the checkbox could be set using the space bar, I saw some unexpected behaviour.
1. If I clicked on a series name or program file and pressed the space bar, nothing happened, as expected.
3. If I then clicked on the Keywords tag name in the tag window, which opened it for edit, and then clicked on it again to close the edit, then pressed the space bar, the first file in the series starts to play. When I mouse up to the top of the screen the Media Controls pop down as usual and I can stop playback.
2. If I clicked the tag name of a checkbox field and left the field "open" for edit, and then pressed the space bar, the first file in the series starts to play. When I mouse up to the top of the screen the Media Controls
do not pop down as usual. I have to use Ctrl-1 to get back to Standard View and stop playback there.
3. If I then click on the tag name of the checkbox field to close the field for edit, and then press the space bar, the first file in the series starts to play. Now again when I mouse up to the top of the screen the Media Controls pop down as usual and I can stop playback.
Conclusions:
a. Pressing the space bar after clicking on a tag name in the tag window causes MC to start playing the currently selected Series/File, unless the tag is open for edit and "space" is a valid input. In contrast, pressing the space bar when just highlighting the series or file in a view does not cause MC to start playing the file.
b. Leaving a tag field in the "open" for edit status prevents MC from displaying the Media Controls at the top of Display View.
Neither sound right to me.