pentax k10d flash query

can someone please advise whether my k10d is behaving properly. I have not been able to explain this from the manual
I have used flash a lot on a Z1p with 28-105 FA lens and frequently use the Hyp mode. This enables one to alter the shutter speed up to 1/250 using the front dial irrespective of ambient light levels.
On k10d using the P mode I expected to be able to set the speed up to 1/180. When i used this in poorly lit interiors, 28-105f4~5.6 FA lens,when I first turn on the flash then the speed is 1/125 and sometimes i can increase speed. lens is at max aperture.
If I reduce the speed setting to say 1/30 then I cannot increase back If I fire the flash I still have the same situation.
If I use the 50mm f1.4, then I retain the full speed range but the aperure increases as speed changes.
It appears the settings respond to ambient light, so the flash speed is dependent on that other than the initial set up when powered on- the intial setting seems to relate to the focal length- longer lens, faster speed
( similar to Z1p )
I can retain full speed range with the flash on Tav setting.
these observations apply with the built-in flash and dedicated external flash
Grateful for any advice

Samething happens with my K10D. It looks to me like there is a glitch in the software somewhere. To go around that, I just turn it "off" and "on". It is a pain, but since I'm generally in no hurry when I'm working with flash, I can manage. Most of the time, when I work with flash, I'll be full manual, since I like the control I have that way.