Advertisement interval > 4 seconds cause problems.

I use extended sleep mode and modified the advertisement interval. Setting intv_min and intv_max up to 6400 everything works as expected. An advertisement package ever 4 seconds.
但是如果我将时间间隔设置为8000 (nd higher) instead of every 5 seconds, I got an advertisement package every 10 seconds. Every second package got dropped. From the current consumption I see how the BLE is switched on, but after 500us it gets switched off. After 5 seconds all 3 packages got send perfectly.

No clue whats wrong.

Thanks and regards
Armin

Update
It seems the code below in app_ps_scheduler.c:app_rwip_sleep_check() isn't returning false to cause the break on every other interval.
if (!lld_sleep_check(&sleep_duration, rwip_env.wakeup_delay))
break;