Related Products filtered by tag

I'm in the trial period, evaluating moving our store from self-hosted to Squarespace. We sell two kinds of fruit preserve in both seeded and seedless varieties. I want to: 1) Use Related Products to display only the seedless products when viewing the seeded version, and/or 2) have a link in the product description of, say, seedless blackberry to go to the seeded blackberry product. (I recognize that I could have one product with two variants, but I don't want to do that.)

The documentation says I can filter by tags, and I have added tags to these products, but there's no place to select/enter the tags I want to filter on, contrary to the manual. For example, "Related products display on product details pages based on category or tag."

Similarly, in the documentation on links, it says: "Select the collection page you want to filter, then select a category, tag, or both from the corresponding drop-down menus. If you select both a category and a tag, only items with both the category and tag will appear when visitors click the link." There is no visible UI to select tags.

Is this one of those Premium features unavailable to me in a trial?

I managed to get tags to show up in Related Products. For some reason the tags I had set didn't "stick" until I did it three times. There is still no support for linking by tag in a product description.

1 hour ago, CheshireGarden said:

For some reason the tags I had set didn't "stick" until I did it three times.

For each product? Or just one product 3 times and then all other tag worked as expected?

I tried to add tags to all the products several times. Possibly I missed a keystroke (found I needed to hit tab or comma to get the text converted to a keyword). I do find that there are times I have to refresh a page or switch to another page and back again for some of the operations to work.