STA connection fails in AP + STA mode

[rayf15]

Hi,
I have a product using ESP32 configured in AP + STA mode. The application running on it usually works, but sometimes ESP32 disconnects
and its next connection as STA fails and starting from this moment on there is no way for reconnection to the external access point, even if the reconnection is periodically forced by my application code and the external access point is yet available. To be noted that my reconnection code has been tested and can accomplish its aim, so I doubt about something that happens to the wifi stack...
In fact I noticed that the ESP32 disconnects when there are console/debug messages coming from wifi stack such as:

I (208783396) wifi: bcn_timout,ap_probe_send_start
W (208783396) wifi: alloc eb len=76 type=2 fail, heap:480
W (208783397) wifi: m f probe req l=0
W (208784396) wifi: alloc eb len=76 type=2 fail, heap:356
W (208784396) wifi: m f probe req l=0
W (208785396) wifi: alloc eb len=76 type=2 fail, heap:480
W (208785396) wifi: m f probe req l=0

My production application is using an old esp-idf v3.1.1.

Do you have some clues about this problem and how to decode wifi log messages?

Thank you in advance!

rayf15