I haven't tried "BitPay wallet", and it is possible they use legacy addresses. Either way, if it's a self-custody wallet, you should be able to extract the keys or recover them from your seed phrase using
iancoleman.io/bip39.
I just installed Bitpay wallet on my mobile to see how it works.
Bitpay generates a segwit wallet for bitcoin and it displayes each bitcoin cash address in two formats. Legacy format which starts with 1 and CashAddr format which starts with q.
So, it's possible that OP made a bitcoin transaction to the address generated by Bitpay for bitcoin cash in legacy format.
Bitpay gives a BIP39 seed phrase for the wallet and it should be possible to recover the fund, but I couldn't generate the same addresses in electrum. Maybe, Bitpay uses a non-standard derivation path.