This answer is probably not helpful for the OP's case, since they're saying that they've tried using different queries, but here's what I had to deal with and how I've solved it in case anyone stumbles into the same problem as I have.

I am unaware if they're using different databases, however from what I understand (from what I think was another Stack Overflow question that I've now lost), the Text Search API requires more strict queries, preventing developers from using ambiguous search queries. This small detail made me lose my mind for around an hour trying to retrieve results I was expecting and failing to do so.

In my case, I was trying to set a location bias with a circle of 10 km radius with the center located in the center of my search area (e.g. Greenwich) and supplying a generic search term (e.g. "Restaurant") to the request, which led me to only receive at most 5 results. What fixed it for me was setting a more strict search query (e.g. "Chinese Restaurant Greenwich, UK") which yielded the results I was looking for.

If your use-case requires you to use ambiguous queries, I think a good alternative could be to use the Autocomplete (New) API in conjunction with the Place Details (New) API.