It's probably a bug with the CoinGecko API/interface.
I tried a different currency and source and could see prices from 2017, but not for USD.
In both Android and Linux versions.

A long time ago I made some Bitcoin transactions on a cold storage wallet.
I recently tried to check my balance with a watch-only wallet and made a new transaction. The transactions synchronized and everything works, except that the Fiat rates show "No data" for the old transactions.
I configured USD as Fiat and tried all possible sources, all show the same.
I can see the historical rates on the CoinGecko website (for example: https://www.coingecko.com/en/coins/bitcoin/historical_data?start=2016-09-20&end=2016-09-21), so I'm wondering: is this some bug or deliberate limitation of the Electrum app?