SXT LED didn't work fine!!

I got a problem of SXT.

I have two SXT briged,one of SXT signal LED always very low,but the real signal is very high !

But the second one did not have this problem!!!

my routeros version is 4.17,i have tried to upgrade to Version 5.0,but it still the same!!

i just test it …

it is the RouterOS software bug !!!

when the SXT works in bridge mode…the signal LEDs only one LED lighting!

the next works in station pseudobridge mode , it works fine!!!

the signal LEDs will show the signal only in th station mode as it is written in the documentation.
For the AP it lights up the first LED when the client connects.