Can't burn bootloader with MicroCore >= 2.4.1

[LoZioo]

I'm having trouble flashing the board's bootloader from core version 2.4.1 onwards. I'm using Arduino IDE 1.8.19 and an Arduino as ISP as the programmer; using core version 2.4.0 doesn't cause any problems, but updating to 2.4.1 or later gives the following error:

Avrdude version 8.0-arduino.1
Copyright see https://github.com/avrdudes/avrdude/blob/main/AUTHORS

System wide configuration file is C:\Users\...\AppData\Local\Arduino15\packages\MicroCore\tools\avrdude\8.0-arduino.1\etc\avrdude.conf

Using port:                  COM6
Using programmer:    stk500v1
Setting baud rate:      19200
Setting bit clk period: 32.0 us

Error: cannot get into sync
Error: cannot set Parm_STK_SCK_DURATION
Error: unable to open port COM6 for programmer stk500v1

Avrdude done.  Thank you.

I suspect the problem is that MicroCore version 2.4.0 uses Avrdude 7.2-arduino.1, while MicroCore version 2.4.1 uses Avrdude 8.0-arduino.1. However, I can still upload the empty sketch even with the latest version of MicroCore installed, so the problem lies with the "Burn bootloader" function.

Flash command generated by the Arduino IDE:
2.4.0 (working): C:\Users\...\AppData\Local\Arduino15\packages\MicroCore\tools\avrdude\7.2-arduino.1/bin/avrdude -CC:\Users\scdad\AppData\Local\Arduino15\packages\MicroCore\hardware\avr\2.4.0/avrdude.conf -v -pattiny13a -cstk500v1 -B32 -PCOM6 -b19200 -e -Ulock:w:0xff:m -Uhfuse:w:0xfb:m -Ulfuse:w:0b00111010:m

2.4.1 (not working): C:\Users\...\AppData\Local\Arduino15\packages\MicroCore\tools\avrdude\8.0-arduino.1/bin/avrdude -CC:\Users\scdad\AppData\Local\Arduino15\packages\MicroCore\tools\avrdude\8.0-arduino.1/etc/avrdude.conf -v -pattiny13a -cstk500v1 -B32 -PCOM6 -b19200 -e -Ulock:w:0xff:m -Uhfuse:w:0xfb:m -Ulfuse:w:0b00111010:m

Btw awesome framework! I love using the inexpensive ATtiny13a for very small projects!