Strange Minus Front behavior when Type contains a slash character?

So I keep having this strange, repeatable issue. There is a strange artifact when using a slash "/" character before a word containing a letter with a circular full closure (O, Q) following it.

1. Create a new document
2. Create a rectangle with the Rectangle tool
3. Insert the text "HIGH / LOW", or "RUN / STOP" in Helvetica Bold over the top of the rectangle using the Type tool
4. Select the text and select Type > Create Outlines
5. Select all objects and click Pathfinder > Minus Front

Predictably, this cuts out the text from the rectangle behind. However, there is an unexpected triangle shape connecting the bottom of the slash to the top of the "O". How to avoid this? I've already tried dividing the background object and ungrouping the outlined letters and doing a Minus Front individually, but this is tedious and I have a lot of objects like this. It also works normally with other text (without a slash or without an O or Q), and with other fonts (Myriad Pro, Skia, for example). With Arial, it did the same thing.

Is there a way to avoid it and have the text cut out predictably?

To reproduce:

Select the text:

Type > Create Outlines:

Select all > Pathfinder > Minus Front:

This only happens with a slash and an "O" or "Q" in the following text. Otherwise it works predictably (even with other enclosed letters like "D").

Any ideas? Is there a better method that might avoid this? (I've only been using Illustrator a few days)