Having some wallet decryption issues…

So I mined a bunch of RVN when it initially launched and also picked some up here and there at the time, I've got about 30,000 in a wallet that I've used to both send and receive several times in the past. I tried recently to send some coin and the passphrase I wrote down doesn't seem to be working properly, although I vaguely remember in the past having a similar issue which was then resolved (maybe I just remembered the passphrase at the time and now can't recall?)….

I have the mnemonic phrase and backups of the wallet.dat file all over the place (I've carried it cross-device in the past). Is there any other way of accessing my wallet or restoring it and gaining access without the encryption passphrase?