Bluetooth receiving but not sending files in OS Big Sur

With Mac OS Big Sur I can receive files by bluetooth but I can’t send them. I have recently upgraded my OS which is installed on my MacBook Pro from Catalina to Big Sur. I can transfer files from my Android (version 10) phone to my MacBook Pro using Bluetooth, but I am unable to transfer files from the computer to the phone. The two devices are paired but when the phone is invoked in the Bluetooth window the connection drops after a couple of seconds. What’s more there is no “send” button alongside the name of the phone as there was when I used it successfully under OS Catalina. I removed “com.apple.Bluetooth.plist” and rebooted and I reset the bluetooth controller, but it still doesn’t work.