does it help to quit all other apps on your device and restarting the device?
What device? What iOS version?
I tried on my iPhone with iOS 14.3, captured 25 HDRs + "Keep Original" DNGs, and these processed OK for me in my free (not subscribed) Lightroom.
Did anything on you device change recently? New iOS version? New iOS settings?
Can you explain "After sometime I export them by iTunes"
Do you mean you used File Sharing between iOS --> Mac OS? (like this:https://support.apple.com/en-us/HT210598 )
I also tried this with no problem. Even after I deleted my Lightroom app cache, the remaining unprocessed HDRs completed processing.
If you can share more steps or info for your problem, it would help. I will send you a direct message to ask for a diagnostic log.
Hello again 'enze5C1D'
We received your diagnostic logs. Unfortunately, the logs do not help us understand the cause.
I see you are running iOS 14.5 Beta -- I tried this on the same device you have, and multiple times I captured 50 HDR images or more and they processed smoothly with no crash.
I do see low-memory may be an issue. Do you have many apps running? Does it help if you quit all other apps? You already said you did this, I think. But I want to confirm this is true.
Please try this if you can: make a full iTunes or iCloud back up of the device. Then Restore the backup. Does this help?