I've used the Paho APIs in Python, C and C++ and moved on to not using any of these APIs. Where possible I use mosquitto_sub and mosquitto_pub to support the protocol and then just read/write standard input/output. It's not a matter of bugs (though I have encountered at least one) but rather it's just easier to use a program that's been written and tested to manage the connection to the broker.

The only place where I was unable to do this effectively was with the last will and testament message (and I might not have tried hard enough.) It also doesn't work with microcontrollers that don't run something like Linux.