I have the same problem with Bias shots. I logged this as an issue and Jasem advised me to install the latest Kstars but I have already got it installed so waiting for a further reply.
I start off the sequence and whirly gig icon goes around but nothing happens. I find if I stop (the square button) the queue then re-start clicking the play arrow it runs. I used to see a message asking me to confirm the camera was covered. I don't see this now but it seems the software is waiting for a response to continue, at least its an impression I have. As I don't have an automated means of blocking light then a manual intervention is ok but some might want to turn it off.
Just out of curiosity did you get Error 50 on your 450D? All of a sudden for me as well, Kstars constantly crashes and my canon 500D has failed and no longer works. My not be anything of significance but this post did catch my attention.
I was running this version as well, it still crashed aplenty (may or may not be related).
My particular problem was almost certainly two things in conjunction:
Much larger camera files (new camera)
Astroberry most people get is a 32-bit OS (and may not even have a 64-bit OS)
The only thing I can guess for me due to the errors I saw while
attaching gdb to the Kstars process
thread and running until it died was that there were memory allocation errors due to the size of the RAM buffer available - so it would attempt to allocate the RAM necessary to hold the image in the viewer(s) and would have a Very Bad Time. Running completely without the EKOS summary viewer and FITS viewer was fine, but not being able to see your resultant images isn't ideal. Running Kstars to connect to the Pi remotely was okay (disabling the viewers on the Pi side, but leaving enabled on the remote host side), but there are latency issues with those large images that can cause weird hangs as well, though you then happily offload the image rendering to the remote host for the viewer(s) versus the Pi handling that lift.
What I ended up doing was actually shelling out for Stellarmate (both for the fact that it has support staff as well as offering a 64-bit version of the OS) and have had absolutely zero crash problems since then. The memory allocation pattern for the viewer also looks way more reasonable and doesn't have large spikes while rendering the images, as though Kstars has pre-allocated a RAM buffer to use versus "just-in-time" allocation.
I am on 3.5.8 as well. The workaround for me is to disable the FITS viewer then I don't get the crashing when imaging.
I should say I didn't experience any crashing when I took lots of bias frames with FITS viewer on during the day, only experience frequent crashing when imaging at night whilst attempting observations. When I took the bias frames I had everything connected up just didn't turn the mount or dome on.
It seems crashing only happens with the observing sequence of focusing, aligning, guiding then imaging.
Running Kstars in the debugger and see lots of theses messages:
Dispatch command error(-1): INDI: Could not find property CCD_TEMPERATURE in ZWO CCD ASI120MM Mini
<setNumberVector device="ZWO CCD ASI120MM Mini" name="CCD_TEMPERATURE" state="Idle" timeout="60" timestamp="2022-04-08T11:23:03">
Strange but looking at the Indi Tab for the guide camera or selecting it in the imaging TAB , the temperature is being displayed.