Guys, I found the solution and would love to share my detailed trouble shooting steps with you all, as the only real solution in this forum that could potentially help you out. I know how frustrating it can be, causing losses in our business every second because of this issue. Luckily, I was able to get this problem solved and successfully renewed our membership, after researching and fumbling in the dark for two days. Please read the following carefully:
1. Find the EXACT Apple ID account where you made the last membership subscription renewal.
Note: it may not be the same as the Account Holder of App Developer. If you have multiple accounts and are not 10000% sure which account, I strongly recommend you to login to different accounts UNTIL you find the one where you can locate that membership subscription under Payment History, or if that developer membership subscription shows up under Subscriptions.
? Where can you see Payment History/Subscriptions of an Apple ID? Follow this step on your iPhone: Settings>Apple ID profile tab(on the very top)>Media & Purchases>View Account>Purchase History/Subscriptions
2. Once you found that EXACT account you made the purchase, you're half way there. Now, change the country of this account to the country where you've made that membership subscription last time OR to the country where you initially subscribed to this App Developer membership.
Seems like you can only be able to subscribe/renew your membership through the same country where you made the last renewal, OR where you've agreed to App Developer Agreement. In my case, those are the same country, so I couldn't figure out the distinguisher. Please try out the possible countries one at a time, follow step 3 and repeat, if you potentially have a lot of options.
? The reason behind this? I'm guessing it's because there might be some legal agreement concern that is regional.
3. Finally, you will be able to see the Renew button again in the Apple Developer App, once you've done the above steps. You might need to login through the Account Holder Apple ID in the Apple Developer App, however, for the Renew button to show up, you need to follow step 1, find that account, and follow step 2, try out countries where you might have agreed the Developer Agreement at.
Above is what helped me to suddenly saw the renew button popped up on my screen. And my thinking for the reasons behind. Hope it's helpful for you and everyone here researching in this forum who's been struggling for this same issue.