Update:
Issue with interrupt gating never solved, I generated a workaround mapping unmasked interrupt signal to uController and managed it in software with some overhead till get solved.
Also reduced USART channel produce overhead to multiplexer, but this is the only solution I found about.
About pin found on HI Z, design stopped working on another core, so I realized the two USART interface where swapped by name on design.
After this both pin (LA and uController got driven low as expected.
Issue is still severe on internal at almost output pin driver still work same way on top level.