Recover files without master key and vault

Hi all,
I just started with Cryptomator 1.17. I installed it, created a vault, filled it with files, and I thought I locked it. I had some other comupter issues and made a hard-reboot. Afterwards, I wasn’t able to unlock the vault, and I saw that both masterkey.cryptomator and vault.cryptomator weren’t there, no backups, just the d folder.
I followed the advice of an older thread on the same issue: Recovering vault when masterkey and vault.cryptomator missing - #10 by infeo
In essence, this made me downgrade to 1.5.17, copy the masterkey and vault files of another new vault in my own one, reset the password with my recovery phrase.
Then, things got complicated (as if they had not been before): I couldn’t unlock the vault with 1.5.17. No problem, I thought, it’s maybe because both the old and the new .cryptomator files were generated with 1.17. So I re-upgraded to 1.17 and attempted to open, but this did not work either, but this time I have the error code:

Error Code G50O:ME3Q:ME3Q
org.cryptomator.cryptofs.VaultKeyInvalidException: Failed to verify vault config signature using the provided key.
	at org.cryptomator.cryptofs@2.8.0/org.cryptomator.cryptofs.VaultConfig$UnverifiedVaultConfig.verify(VaultConfig.java:203)
	at org.cryptomator.cryptofs@2.8.0/org.cryptomator.cryptofs.CryptoFileSystems.create(CryptoFileSystems.java:52)
	at org.cryptomator.cryptofs@2.8.0/org.cryptomator.cryptofs.CryptoFileSystemProvider.newFileSystem(CryptoFileSystemProvider.java:196)
	at org.cryptomator.cryptofs@2.8.0/org.cryptomator.cryptofs.CryptoFileSystemProvider.newFileSystem(CryptoFileSystemProvider.java:86)
	at java.base/java.nio.file.FileSystems.newFileSystem(Unknown Source)
	at java.base/java.nio.file.FileSystems.newFileSystem(Unknown Source)
	at org.cryptomator.cryptofs@2.8.0/org.cryptomator.cryptofs.CryptoFileSystemProvider.newFileSystem(CryptoFileSystemProvider.java:126)
	at org.cryptomator.desktop@1.15.1/org.cryptomator.common.vaults.Vault.createCryptoFileSystem(Vault.java:147)
	at org.cryptomator.desktop@1.15.1/org.cryptomator.common.vaults.Vault.unlock(Vault.java:166)
	at org.cryptomator.desktop@1.15.1/org.cryptomator.ui.keyloading.KeyLoadingStrategy.use(KeyLoadingStrategy.java:79)
	at org.cryptomator.desktop@1.15.1/org.cryptomator.ui.unlock.UnlockWorkflow.call(UnlockWorkflow.java:82)
	at org.cryptomator.desktop@1.15.1/org.cryptomator.ui.unlock.UnlockWorkflow.call(UnlockWorkflow.java:37)
	at javafx.graphics@23.0.1/javafx.concurrent.Task$TaskCallable.call(Unknown Source)
	at java.base/java.util.concurrent.FutureTask.run(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$UniAccept.tryFire(Unknown Source)
	at java.base/java.util.concurrent.CompletableFuture$Completion.run(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.base/java.lang.Thread.run(Unknown Source)

This directed me to the following post: Error G50O:P31S:P31S · cryptomator/cryptomator · Discussion #2128 · GitHub
But this post is about opening another vault with the wrong key, which is not my case. I have the right key, but the vault.cryptomator file is signed with another key. I want to force-open the vault with the correct masterkey. How is that possible to recover my files?

Thanks
Philippe

An update on this issue: I managed temporarily to have access to my files again. What I did was that I needed to downgrade to 1.5, create a dummy vault with 1.5, copy the vault.cryptomator and masterkey.cryptomator to the folder with my files, make a recovery with the initial plaintext recovery phrase to reset the masterkey. After upgrade to 1.15, I could open the vault again, but needed to update the vault version. I was able to access th access the files then.

However, some time later, I ran into the error that I cannot open any of my old files. It consistently gives me an I/O error in windows. I can however open new files which I created meanwhile.