I believe the problem is solved and you will never believe what the culprit was. Let me recap first as a gentle reminder: I use iCloud to sync all of my data and apps that can be synced to the cloud. Here are a few of the symptoms that I experienced that led me down this path (full details are in my initial post) My iPhone 15 Pro Max has 1TB storage. Device was never dropped. Zero water, dust or other damage. Always in a good case to protect from drops etc. About 8 months ago my phone started running hot. Not the normal heat but to the point where you could barely hold it - scalding type of hot. There was no explanation as to why my device was running hot. Yes I'm a heavy device user. Yes I have tons of apps including games but no reason for my phone to be this hot. I simply dealt with it for this long period. Eventually in January my phone stopped backing up to iCloud. Last good back up was late January. I was convinced it was my device and a hardware issue. I resolved myself to buy another device and give up on the current one. Apple support run a hardware diagnostic and all clear was given. I was not fully convinced. Additionally, about 4 months ago my device began to periodically lag and freeze while using various apps. It was most noticeable when typing in any app - Word, mail, etc. You'd type and it would take 20-30 seconds to catch up to your keystrokes. The last straw was the failed iCloud backup. Even if I wanted to replace the device a good current bacup would be required. You can see all the details of my plight in my initial post.
Eventually, I stumbled on my contacts having almost double the actual number of contacts with the issue being duplicates in my contact list. For example I have approx. 860 actual contacts but my device showed approx 1,400 contacts. I thought nothing of this as my device was "glitching" over something. This was just another symptom I thought. Phone was running hot, lagging and freezing, at various times it would take over a minute to hang up after completing a phone call. (the screen would show the disconnecting visual but my my device phone function would just lock and it would grey/ghost out the phone feature). One day I noticed a contact that I had not designated was featured in "My Card". When I tried to change it back to my info it would not delete or update. Even with all the issues that I was having this was a new level of PIA. I tried rebooting (have been doing that for months) and no luck. I noticed the option to merge the duplicates (somewhere between 6-7 hundred dupes). When I tried to merge "all" the operation would just lock up the contacts app. I would have to force quit contacts. After multiple tries, I tried to merge the individual contacts that ere duplicates (one by one). This only partially worked - some would in fact merge. Others would result in the contacts app crashing. It was hit or miss. I manually went through every single duplicate contact either deleting dupes or merging the ones I could. This process took hours. At the end of this operation I was just happy that "My Card" was back to displaying my info. I didn't think much of it as I just figured I fixed my contacts. I went to bed with my phone on power and locked and connected to WiFi with zero expectations. The next morning - - a successful backup had occurred.
The culprit was a corrupted contacts app. My phone now consistently backs up. My phone no longer lags/freezes. My phone is now operating at normal temperatures.
Hope this information helps someone else. :-)
