Are you retiring through Social Security in July? If so can you provide the amount of your monthly payout?
If not, you must qualify based on assets alone. It's not as straightforward or simple, but it's done all the time.
As a former loan officer, assets never meant nearly as much to us as income--assets can come and go, be spent, garnished, levied, wasted, invested poorly, gambled, depleted, or even stolen, but an income stream is a stable prediction of future ability to pay. One can have $80,000 in an account today, and go out and buy an $80,000 car tomorrow and have no money. The US Treasury generally doesn't even tax or track assets, only income.
But that is merely to say that income is the *preferred* and most secure method of proving ability to pay. Proving ability to live off assets is not a terribly hard barrier to overcome, particularly for retirees. In fact, that's typically the only way many retirees have of proving wealth, and it's a common element of many retirement visas in foreign countries, and is done every day. Based on what you have posted, it seems you are financially qualified based on assets. The only issue is providing the documentation requested (cash account, proof of account ownership, etc. based on the immigration rules).
Rejections could be for a number of reasons. I had a tax return rejected because it was missing ONE schedule from the dozens of pages of the return. The contents of the schedule didn't affect my income threshold at all. My income alone was well above the qualifying limit, but because I didn't include some obscure schedule (I dont remember--like a $25 stock dividend payment or something silly--which I didn't even need to prove minimum income--the form was rejected. I finally uploaded all the schedules (twice--it was rejected the second time!!) and was accepted in the end. I could have freaked out and said "WHY are they REJECTING me in proving my INCOME! I have PLENTY of INCOME" but that wasn't the issue at all... they just required ALL schedules and unless I had all schedules the fact that my salary alone qualified me easily didn't matter. So it's likely those who were rejected didn't follow the rules. Just follow the rules fully and make sure you are proving the ability to support based on assets as they have described in the instructions, not just showing a number in a bank account balance.