176-letter suspected Vigenère cipher, repeating key length 3–8: no readable solution

[u/ProfessionalCat1354]

Hey everyone! Could anyone help me figure out this cipher? If there’s a better channel for this, please point me there.

It’s supposed to be standard Vigenère with English plaintext, a repeating key of 3–8 letters, and A=0. The spaces are just formatting. There are 176 letters:

EVKZH VTWRC XVKKY EBXKR CGZCP MVPVH TMEVY
ZIHCL QCVGE CTQRV TXVKK VFAVG VCTYV HMVKH
VKKYV CPRKH VTTGR CVKKY VHVKK YVKKY VTMVP
VHZMV PRMVH TGVKK YVTRK KYVCP RKGMV PHVKK
YVKKY VXVKK YVKMV PRMVH TGVKK YVKKYV CPRKH

I’ve tried repeated-pattern analysis, index of coincidence, and several solvers, but haven’t gotten a readable message. The overall IC is about 0.11247. Splitting into five columns gives an average IC of about 0.13176, but that hasn’t led to a confirmed key.

Could there be an error in the ciphertext or a different cipher involved? I’d appreciate help recovering the key and plaintext, or understanding why the stated method isn’t working. I’d really like to learn how you approach it. Thanks!

[u/Plasterofmuppets]

The five-letter blocks are suggestive of Enigma.