On Windows & Mac there is a setting that automatically keeps your clock in-sync. If this setting is turned off, it will cause issues when attempting to clock in to General Tasks in Tymeshift.
For example: If you manually adjust the time of your computer clock, this will cause problems.
Here's how to fix this issue on Windows:
Here's how to fix this issue on Mac:
NOTE: After you ensure your clock is set correctly, you must completely quit your browser and re-open it. After that, you should be able to use Tymeshift to clock in and out again normally.