I have been struggling with the chainable LEDs for more than a year now.
I had exactly the same problems and reported it.
Recently Karan made a new library where the LEDs are no longer connected to a digital port but to the RPISER port.
I am using it now for more than a month without any errors.
You can find it under the 'direct_ser_lib’
It was a clear solution for me as it functions perfectly now.
He recently added the possibility to set the colour of one led with a command called ‘.setOneLED(e,g,b,lednum)’.
I do not know if it is also already implemented in the github library as he added this specially on my request.