Invalid prev_hash when trying to sign transaction with Trezor T (in Firo Electrum)

I think since beginning of august I’m having this issue in Firo Electrum where I can’t sign an outgoing transaction with my Trezor model T

Everything shows up on the screen as normal, last step is to press and hold to confirm … and then I get this message

RuntimeError(‘ProcessError: Encountered invalid prev_hash’)

I had this exact same issue a week ago (when I last used Firo Electrum), I was able to send small amounts, but then when I wanted to send a larger amount of Firo I got that invalid prev_hash for the first time. Somehow managed to make it go through after several attempts.

Today again, I can send like 1 Firo to one of my other firo addresses, but when I do a large amount I get that error again?

Trezor firmware is the latest 2.5.1, Firo Electrum on mac
Trezor suite also the latest version, but don’t have that open while interacting with the Firo Electrum wallet.

Any idea what could be wrong? I didn’t have any issues until at least july 14th

I’m thinking it has something to do with me trying to send coins that were only recently added, that would explain why sending 1 firo of my “old” balance works fine, but when I try to send an amount that requires using the newly added firo, it doesn’t want to do it.

update: just tested firo electrum + trezor on a windows machine, getting the same invalid prev_hash message while it’s trying to sign a transaction.

I’m now on trezor firmware 2.5.2, in windows trezor suite had a notification there was a newer firmware, while on macOS 2.5.1 seems to be the lastest as it said “up to date” while I was on 2.5.1

anyway, still same error on windows and mac, firmware 2.5.2

I’ve traced it down to a transaction about coins from masternode rewards … when I freeze those coins, I can send all other coins.

Strange, I know masternode rewards need 100 confirmations to become spendable, but these have 25K+ confirmations already.

there is a solution here, if it does not work I suggest contacting their developers.