I worked with a M5Stack, Arduino 1.8.x and MacOS Mojave and every thing with USB was fine.
I updated to MacOS Catalina and updated Arduino to version 1.8.10. Every with USB for my M5Stack was fine, too. If I check the USB driver I can see:
$ ls /dev/tty.* /dev/tty.Bluetooth-Incoming-Port /dev/tty.SLAB_USBtoUART /dev/tty.usbserial-017D2264
If I like to flash my M5Stick-C and I connected it, I can see only this:
$ ls /dev/tty.* /dev/tty.Bluetooth-Incoming-Port /dev/tty.usbserial-9D5AE08545
With the old and the new Arduino-version the "tty.usbserial-9D5AE08545"-driver did not work. Arduino needs a "SLAB_USBtoUART"-driver.
What can I do?
Yes, I know today Catalina is a beta-version, but it will released shortly.