Hi K0lo I am very interested in your problem as I two have the same issue starting back on Feb 3 or 4 .
I have looked extensivily into task scheduler to recreate a start point to test this , it fails consistantly also I have checked all the shadow copy writers ,copies ,volumes and they seem to be in order and working. I have searched thru the registry and can
also see the keys related to the indivdule shadows but I have no previous versions or restore points .
The only way I have found to create one , is to manually create a restore point and that remains but no others appear after system checkpoint should of been created.
I do have bitlocker enabled from usb ( i dont have a TPM) and think this maybe something to do with the problem. I have disabled it once and I had some previous versions reappear ???(amongst a million other configerations) My next move will be to decrypt the whole drive 60+gb of data and try with no bit locker enabled. Do you have bit locker enabled? Please let me know how your going with this issue as I have searched high and low for related info on this issue I was supprised when I saw your post as is exhactly the same I am sure there will be others with the same regards thecheif