Could you post some pics of the razor? It could be a number of things, but with pics it might be easier to give a good answer.

Off the top of my head, some possibilities include:

Uneven spine wear (is it a new or vintage blade?)

Wonky (i.e. not straight) spine

Uneven pressure having been applied either by you or previous owner/honer, hence new vs vintage question above.

Are you sure your hone if FLAT? Not just flat, but FLAT!

I'm sure others will chime in soon with other suggestions, but after a long, long day today, that's all I can think of at the moment.