Why do I have to pay gains tax on last Summer's Byron to Shelley Upgrade?

My accountant entered my Daedalus input into Koinly.
I have been in possession of my ADA for over 3 years.
Koinly has categorized my Daedalus ADA as a HUGE green gain.
I have never traded my ADA balance. I simply moved it from one Cardano wallet to another. There is no history connecting my Byron and Shelley wallets.
I have restored Byron and it only shows 14 transactions but they’re from December 2017-end of May 2018. There is nothing from May 2018-June 2020.
The fall of 2018 i purchased most of my ADA. There is no record of it in Byron right before the wallet switch. There is however a record of the deposit in Shelley.
This is going to cost me thousands of dollars in income tax.
I can’t find any useful info to track my Daedalus properly.

See the answer to Q38 in the IRS FAQ on cryptocurrency:

If you transfer virtual currency from a wallet, address, or account belonging to you, to another wallet, address, or account that also belongs to you, then the transfer is a non-taxable event, even if you receive an information return from an exchange or platform as a result of the transfer.

P.S. If you look up the Shelley deposit transaction on https://explorer.cardano.org, it should show that it came from the Byron addresses.

Ok I will try that when they are done maintenance.