I currently have Jetpack 5.1 installed on WP 4.8.1. The Updates page says an update is available to Jetpack 5.2.1 but also says “Compatibility with WordPress 4.8.1 unknown”. Meanwhile if I click the 5.2.1 view details link the overlaid lightbox says “Compatible up to: 4.8.1”.
I do see the “Update to the latest versions” message that is requested before posting but I’m hesitant to do so with mixed messages about compatibility. Is the compatibility unknown message wrong, or the compatible up to 4.8.1 message wrong?