FreeRTOS "Assert Failed" crash when starting esp_deep_sleep

Using the latest mos version (2.19.x - 202106171938). I’m occasionally getting a crash when the device goes into deep sleep, by calling esp_deep_sleep_start()

The crash shows the following:

    [Sep  5 13:59:57.704] /opt/Espressif/esp-idf/components/freertos/tasks.c:3095 (xTaskRemoveFromEventList)- assert failed!
    [Sep  5 13:59:57.713] 
    [Sep  5 13:59:57.713] abort() was called at PC 0x4008c490 on core 0
    [Sep  5 13:59:57.717] 
    [Sep  5 13:59:57.717] Backtrace:0x4008b065 |<-CORRUPTED
    [Sep  5 13:59:57.720] 
    [Sep  5 13:59:57.721] 
    [Sep  5 13:59:57.721] ELF file SHA256: 7087c86825e859b7

The device then gets stuck in a permanent boot loop crash until power is physically removed. Has anyone come across anything similar, or can offer suggestions as to what might be causing this. It happens regularly on the latest version, but has never happened once on 2.18.

I’m using an ESP32 Wrover with 4mb PSRAM - single core mode.