is that a problem ?
The problem is that BCH was designed to confuse people. It uses the same address system as Bitcoin, but it uses a different blockchain. So, when you sent from Coinmama, you sent to a BCH address on the BCH blockchain, but your Electrum wallet is looking on the Bitcoin blockchain (not the BCH blockchain) so it can't see it.
Imagine that I live at 123 Main Street in Springfield, Illinois in the USA.
Imagine that someone else lives at 123 Main Street in Springfield, Maine in the USA
Notice that the addresses look the same, but they are in two different states.
Now, imagine that you ask John to send me a letter.
John and you are both in Maine, and John asks you for my address. You tell him: 123 Main Street, Springfield.
John doesn't realize that I'm in Illinois, so he sends a letter to 123 Main Street, Springfield in MAINE!
Now you ask me if I have the letter. I say No. You ask John what happened, John says that he sent the letter to the address you provided and that he doesn't have it anymore. Who has it?
In that example:
I am Electrum. I provided you with an address in Illinois (Electrum gave you an address in Bitcoin).
John is Coinmama. You provided my address to John (You provided the BTC address to Coinmama).
Maine is the BCH blockchain. John sent to Maine (Coinmama sent to the BCH blockchain).
I can't find the letter (Electrum can't find what Coinmama sent).
John says it was sent (Coinmama says it was sent).
So, what you need to do is to go knock on the door at 123 Main Street in Springfield, MAINE and ask for the letter.
In this case, you need a BCH wallet that is capable of using the Bitcoin private keys (or seed phrase) from your Electrum wallet, but looking on the BCH blockchain. By using the
Bitcoin private keys (or seed phrase) it will be looking for the correct address, and by looking on the BCH blockchain it will find the BTC associated with that address.
Unfortunately I don't use BCH at all (as far as I'm concerned, it's a worthless altcoin), so I can't explain how to use bitcoin private keys in a BCH wallet (or which wallet to use to do so). Hopefully someone else will come along shortly and explain that process. However, hopefully my explanation will give you some understanding about what happened and some peace of mind that your BCH coins are still secure on the BCH blockchain just sitting there waiting for you to come collect them with the appropriate wallet software and private keys.