I have a key column and associated keyURL column in the table. I have configured the table with conditional formatting for key column such that the keyURL link is used as a hyperlink. I have also set Totals=On and summarized the Time Spent column.
As you can see in the table visual, when time spent is null I no longer have URL visible for the key, Looks like a bug in Power BI.
This bug is still around as of the October 2021 release.
As long as the row has at least one measure that returns a result the link will work. If none of the measures in the row return a result then the link does not appear. Since sometimes adding a zero to a measure brings back data you don't want, an alternative is to use a measure to generate what what would normally only be in a column. For example if you had a "type" for each of the "keys" you could created a measure:
mType = FIRSTNONBLANK(keys[type],TRUE())
Using the "mType" measure in a table would show the same text as putting "type" in as a column, but it would allow the row to have at least one measure with a result without having to add zeros to a numeric measure.