Here is a workaround for UIFLow2.0:

import M5 import hardware import time # UIFlow2.0 workaround for M5.Power.timerSleep() not working properly # on SOME CoreINK devices. On these decvices the board-power is not # proberly turned off. However, the M5.Power.powerOff() does work # for these devices, i.e. turning board-power properly off M5.begin() #init i2c bus with pins connected to the RTC i2c0 = hardware.I2C(0, scl=hardware.Pin(22), sda=hardware.Pin(21), freq=400000) ##### Put your code here. time.sleep(3) ##### code substitution the timerSleep() function # Set registers of the RTC. ref datasheet for BM8563 RTC for further info # reg 0x00 always 00h # reg 0x01 bit 2-7: always 0, bit 0: enable/disable timer int # 0x01 = timer enabled reg00_01 = bytearray([0x00, 0x01]) # reg 0x0D always 00h - clock out disabled # reg 0x0E bit 7: endable/disable timer, bit 0-1 timer resolution # 10=sec 11 = min # 0x82 = int enabled and seconds resolution # reg 0x0F timer value 0-255 # 0x14 = 20d = 20 sec. if reg 0x0E = 0x83 then 20 min reg0D_0F = bytearray([0x00, 0x82, 0x14]) # i2c device address of RTC is 0x51 # Write to register address 0x00-0x01 i2c0.writeto_mem(0x51,0x00, reg00_01) # Write to register adsress 0x0D-0x0F i2c0.writeto_mem(0x51,0x0D, reg0D_0F) M5.Power.powerOff() ##### end of code substitution the timerSleep() function

Upon further testing and investigation, my original observation is incorrect. It seems that the blocks are mostly working correctly. It does not seem to be an issue with a specific version either. When I setup a simple UIFlow sketch to "Restart after 10 seconds", the first time I run it it correctly restart after 10 seconds. It then seems that the IRQ register isn't set right because it won't restart again if I immediately run the code again. If I instead power of the Core2 and then power it back on with the button on the side it will then run the code correctly and restart the device. It does not seem to be a hardware issue as the example wake on rtc code in the M5Core2 arduino library works correctly every time.