Upload_speed 74880 not working

Just tried to flash a Sonoff T1 EU. As it uses a non-standard 74880 baud rate, I set that for monitor_baud and upload_speed. Monitoring works, I can see the messages from the device. Uploading does not, with an error saying something like “probably cannot set serial speed”. Using the esptool directly esptool.py --port /dev/cu.usbserial-A50285BI --baud 74880 write_flash -fm dout 0x0 .pioenvs/sonoff/firmware.bin works for uploading. This is on a Macbook Pro / High Sierra with the FTDI drivers installed via Homebrew. Is there some other way to set the upload speed?