For those who use Checkmate, I emailed Micromat about Big Sur compatibility and received the following:

Thanks for the email. It may be a while before Checkmate gets an update to support Big Sur. Currently, the scheduling functions don’t appear to work properly. Our development team hope to have something available in a few months. In the meantime, when using Checkmate under macOS 11 Big Sur, you can hold the option key while clicking on the Checkmate menu bar icon, and choose Start Testing to run Checkmate’s tests manually to get around the scheduling functions issue.


Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365