I'm experiencing difficulties with AirDrop on my old iMac and iPhone X. In photos on the iPhone AirDrop (logo) has recently totally disappeared. (On the phone) I've traditionally used it very successfully to quickly transfer iPhone photographs onto the Mac. The Mac is set to “allow me to be discovered by anyone” & is a Late 2012, 21.5 inch. I'm thinking the possible causes could be either that I have recently upgraded to an external SSD, as my boot drive or that I have not upgraded the operating system to the new version (Catalina). I've checked App Store and all apps are up-to-date I am running Mojove. The iPhone is on 13.6 & that is up to date, according to the phone settings. I don't particularly want to update to Catalina as I know that some of my software will then not work. I'd appreciate any help greatly.