ESP32 S2 espnow/wifi not working when receiving on uart1

[jesse_a_b]

I uploaded the ESPNow Basic Master arduino sketch to a ESP32 S2 (S2 Mini board on ebay) and it works, but if I connect the rx pin (GPIO18) for a serial signal coming from an arduino, the wireless communication doesn't work.

"No WiFi devices in AP Mode found
Slave Not Found, trying again."

However if I only connect the GPIO18 pin after the ESP32 has already started and espnow is connected, then there's no problem.