I've heard all kinds of stories about this. The most often one being a "change of pH" in the soil. The other one is that the chips will "steal nitrogen" from the soil.
Honestly, I don't give either of those too much worry.
What you do have to consider is a thick layer absolutely will create a lot of compost heat for the first few months. Ever see a steaming pile of wood chips? Happens all the time. That can burn roots.
But I don't think you have anything sensitive under there, right?
The second issue with wood chips is they float if you get heavy rain. Many-a-mulched area in these parts have vanished after a rainstorm.
Here in NC, this is termite heaven. In a year, you'd barely realize they were wood chips. Your mileage may vary up in the Pacific NW. These are silent insects for the most part. They just do their job. Not sure if you have termites. No worries, there are plenty of other organisms to have a feast. There are a lot of places, including the city, that give them away. We use them for mulch ground cover all the time. And then replace them after the termites feast and the rains carry them away.