QR code generation with long message

I am using the Arduino QR Code library from GitHub to generate QR codes on a little LED display. It all works fine until my message reaches a length that seems well below the limit of the QR code version.

I am using version 7 (45x45) at low error correction, which should be able to handle over 200 alphanumeric characters. But the codes suddenly become unreadable when the message goes over 153 characters.

I have plenty of memory and program space (ATmega328p), and increasing them (by stripping down the program) didn't help.

Is there something intrinsic to the library that limits the size of the message?

i don't know about the library, but how about you post your code and the links to the library so we can see what could be the problem.