People say that one cannot use ESP-NOW and Wi-Fi (connecting to a regular router to access the Internet) on the same ESP8266. Can any official source confirm this?

There are two ESP8266's: E1 and E2. Both E1 and E2 are set to WIFI_STA, ESP_NOW_ROLE_COMBO for bi-directional ESP-NOW messaging. Additionally, Adafruit MQTT is enabled on E1. The problem is that when I enable MQTT on E1, ESP-NOW randomly fails. Both E1/E2 are set to use channel 1, and the Wi-Fi AP t...