lib_uart ET_ILLEGAL_INSTRUCTION on XU316 XTC 15.3

[avrobot]

When I run multi uart multiple port (8bit ports) on XU316 I get ET_ILLEGAL_INSTRUCTION see below....

xrun: Program received signal ET_ILLEGAL_INSTRUCTION, Unable to decode instruction.
0x00082144 in uart_tx_assemble_word (info=..., uart_char=<optimized out>) at source/lib_uart/lib_uart/src/multi_uart_tx.xc:87

the actual assembly seems to be 0x82144 <uart_rx_loop_8>: entsp (u6) 0xc

Seems lib_uart in multiple uart mode does not work on XU316 using XTC tools version 15.3...

entsp is XS3 instruction that would be illegal if it were run on earlier silicon but this is XU316 that is XS3 instruction... so I am confused.. or maybe root cause is not this acutal line...

How to fix??