Esp 01 does not connect using ESP core version 2.4 or higher and Blynk 0.5.4

Why should how you flash the code to the device affect how OTA works?

And what is with this convoluted if()… just leave your OTA command in the loop() running as fast as it can so as to be able to do its job.

PS works fine on ESP Core 2.4.2 for me