It's a weird situation... I was helping the user on Telegram when they first posted the other evning... using their 12 words seed mnemonic and "legacy" option, Electrum only shows transactions up until the end of June (and a final balance of zero). OP swears there has been activity on the wallet since this date (as recent as last week).
Tried the "p2sh-segwit" and "native segwit" options, but they show no history whatsoever. Even tried using derivation paths for different "accounts", but no history there either. It's like the iOS version of Mycelium just started using a different derivation path at the end of June or something??!?
Addtionally, for whatever reason, even after a delete, reinstall and restore, the Mycelium app on the iOS device was unable to sync properly... hopefully, when that situation is rectified, the wallet will resync correctly and show the correct balances/transactions.
Otherwise, it's going to be a "needle in a needle stack" type of search trying to figure out what the derivation path should be...