I have a similar issue.
I received the following message which said to post it here. I just moved the Dropbox local storage from my C: drive to a larger E: drive to free up memory from C: The data file was on Dropbox.
************** begin error message ***********************
Something went wrong. Please report the issue in our Github
repository with the following technical info.
KeePassWinHello.AuthProviderSystemErrorException:
NCryptEncrypt
Error code: S00704C7
at
KeePassWinHe11o.WinHe11oProvider.SECURITY_STATUS.CheckSt
atus(String name, Int32 ignoreStatus)
at KeePassWinHello.WinHelloProvider.Encrypt(ByteQ data)
at KeePassWinHello.KeyCipher.Protect(ProtectedBinary key)
at KeePassWinHello,ProtectedKey..ctor(CompositeKey
compositeKey, KeyCipher keyCipher)
at KeePassWinHello.KeyManager.OnDBCIosingfObject
sender, FileClosingEventArgs e)
******************* end error message ***********************
Here is version information;
KeePass Version 2.44
XSL Stylesheets for KDBX XML Installed
KeePassLibC (1-* File Support) Version 1.38 (DxD1B2)

I am running on Windows 10 Pro 64 bit Version 1909 OS Build 18363.720
Installed 11/13/2019
Hardware: Home made AMD FX-8320 8 Core processor, 32 GB memory

Originally posted by @rgwebster in #42 (comment)