Hello!
Your SPI data loss when LVGL is running, but not when LVGL is commented out, strongly indicates resource contention or CPU starvation. The LVGL task is likely consuming too many CPU cycles, preventing your SPI task or its interrupt service routine (ISR) from processing LPSPI_SlaveTransferNonBlocking() completions promptly. Increase your SPI task's priority above LVGL's, optimize LVGL's performance (e.g., reduce refresh rate, simplify UI), and ensure no critical sections in LVGL are disabling interrupts for too long. Temporarily reducing SPI clock speed can also help confirm if it's a throughput bottleneck.