Mpesa STK Push payment failure on iPhone with e-SIM

I can't make a purchase with iPhone. Not just me. Everyone else I know that uses an iPhone. Was trying to pay in a supermarket. You provide a phone number and they send an STK Push - a notification for you to authorize the payment. I put the pin but nothing happens. Several flight mode on/off, restarts later still won't work. The attendants say that it is an issue with iphones so I had to go out, withdraw then pay in cash.

I tried paying for something online today at home. Same problem. Merchant sends the request:

With that I should type the 4-digit PIN and that's it. If I have enough money, the transaction should be done in seconds, with any phone. Even the ancient flip phones. But iPhone? Nothing happens. You put the pin and send, but nothing happens. It just times out on the merchant's side:

Does that mean that the iPhone never sends the response back? Is there a setting to make it work?

Without e-sim you have a 50-50 chance of making the transaction go through. If you have e-sim running the chances go to 0. When e-sim is on, just after I send the PIN, the network is dropped completely. Until after some minutes or force restart the SIMs.

Without e-sim, nothing happens. You are waiting for merchant to acknowledge and mpesa to send you a confirmation message, but nothing happens. Only the merchant tells you no response from user.

I know most people around the world are alien to this form of payment but I hope there must be someone with a solution to the problem.

[Edited by Moderator]

Original Title: Mpesa Payment won't Work