LCDBPV2 library has been designed to work well in almost every situation, but may occur that, in serial mode, screen comunication breaks and LCD shows wrong images. This is not usual, but if you use bad the interrupts or do high speed touch, serialized data may not arrive alright and causes malfunction.

To solve this you can use a simple RC filter between the INT signal of LCDBPV2 and the microprocessor like the one that is recommended for Arduino.
This RC filter are made up by 100nF capacitor and 10K resistor. You can use another values.

danirebollo.es