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Hi there
That looks like it could be caused by a conflict with some other plugin (or possibly the theme).
Could you please try to isolate the cause by disabling non-Toolset plugins and switching theme if necessary, to confirm that the editor works normally in a minimal set-up, and then re-testing as you re-activate other plugins and the current theme.
If you can determine where the conflict lies we can try to reproduce the issue so that we can go on to fix it.