Make Feature Layer / Select / Select Layer By Attribute "Get Unique Values" grayed out in ArcMap ModelBuilder [10.8.1]

I’m trying to extract road segments from a feature class through ModelBuilder in ArcMap 10.8.1 based on attribute queries, but the "Get Unique Values" button does not pull up a list of values when I click on it. Of the three tools that I have tried for this (Make Feature Layer, Select, Select Layer By Attribute) they all produce the same non-result.

Below is a screenshot that shows the tools I’ve used leading up to the selection step, and what happens when I try to "Get Unique Values" from these various tools. I know that sometimes ModelBuilder is fussy about which selection tool is used based on whether the data is a feature class or feature layer.

Can someone tell me what is happening and how to make it work?

Cross-posting from GeoNet to try to reach as many people as possible!

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UPDATE

I should mention that if I try to manually type a query into the main Make Feature Layer, Select, or Select Layer By Attribute tool, it won’t verify.

Still haven’t figured out the initial problem, but I did find a workaround by inserting a Calculator Expression from the Create Variable option and linking it to the tool. Hopefully this is helpful!