is there a marked as Solved for this forum?

So your screenshots show exactly what I would expect. With match case on, \u only matches uppercase. With match case off, \u matches either uppercase, or, because it is ignoring case, lowercase as well. That’s how things are defined to work.

If you want to have case-sensitive \u no matter what, use (?-i:\u) to make the parenthesized subgroup case sensitive no matter what the checkbox says:

My apologies for not providing example data.

with match case on:

with match case off:

how do you make $\u and "\u only pull UPPER case instances?

\u only matches uppercase, unless you have case-insensitive match turned on. (If case insensitive is on, obviously uppercase and lowercase will both match, by definition of case insensitive)

I don’t yielded the correct information.

Well, you haven’t given any example data that doesn’t match your expression. That makes it harder to help you. That’s why I pointed you to those posts, because they explain the importance of providing sample data that actually matches the data that you have.

(?-i)[\u\d]\K\x20(?=[\u\d])

That’s a very different expression than I gave you, or than what was necessary to match text in your screenshot. That is saying “turn off case-insensitive-match; there must be an uppercase or digit, then reset the match, then find a space that is followed by uppercase or digit”. That has nothing to do with the example data you showed above.

But given the description I just made, the expression you listed matched everything I expected in my example text below:

range("A1")
range("$I$15:$I$19")

lowercase lowercase
UPPER UPPER
314 159
UPPER lowercase
lower UPPER
314 lower
314 UPPER
lower 159
UPPER 159

It matches the spaces that come between two UPPER, or the spaces between two DIGITS, or the spaces between a digit and an upper in either order. That’s exactly what I would expect.

as well as guiding me towards very helpful artifacts that I should have reviewed.

how do you make $\u and "\u only pull UPPER case instances?

I will read in more depth, but simply searching for \u in an effort to locate how to only pull UPPER case letters I don’t yielded the correct information.

section:
Then use the following regex S/R :
Search for: (?-i)[\u\d]\K\x20(?=[\u\d])

For | to work as logical-OR, you have to be in Regular Expression mode. But in regex mode, $ means “end of line”, not a literal dollar sign.

Regex have prebuilt character classes which will help with your search; in your case, \u will search for an upper-case letter. So "\u will match every time there’s a quote followed by an upper case.

To search for a literal dollar sign, you need to escape with \ it so it will be treated as a literal character: \$. So \$\u will match any uppercase letter that comes after a literal dollar sign.

-—
Please note that your examples sometimes had " and sometimes had “ – those are two different characters. If you had followed the advice given in “Please Read Before Posting” (which you should have seen immediately below the New Topic button that you clicked):

and the advice it links to in the “Template for Search/Replace Questions” and “Forum Formatting Posts” FAQ entries, you would have been instructed how to present your question in a way that left no ambiguity as to which was the “right” quote characters for your data.