SFTP fails with strong private key protection

When I import a private key while enabling the 'Enable strong private key protection' option and attempt to connect to a server with that key I get the following error in the log and the connection fails:

[R] Connection failed (Format '%s' invalid or incompatible with argument)

I think that opening the password prompt dialog is failing and generating this error, may be something with localization (though I use the english language). This effectively means that other connection types that require a password prompt may fail as well.

I think I experienced this error somewhere since v5.0.0 RC1, may be earlier, just found out why, to workaround the bug I re-imported all my private keys with the option disabled to avoid the password prompt.

Hello,

Thank you very much for reporting this bug.

I have confirmed the issue and it appears that this dialog prompt was still using the old legacy code from v4.x which is completely different from the new style used in v5.0. The prompt contained several flaws, one of which resulted in this error.

I have updated the prompt to use the new v5.0 style and logic, and I am performing some additional testing, once I have completed my tests I will provide you with a download link to the new build so you can confirm my fix.