texan

I selected the mask and did the invert command (CTRL I). The mask inverted.

I did, R C-R, and the mask inverted. When I painted white on it, though, nothing was revealed while the mask icon indicated that I had painted on the mask. (After inverting the mask, hovering the paintbrush over the mask revealed "clear paint".) I've just spent over an hour on this same tutorial as the OP and am relieved to see that this is a bug. I tried over and over again, carefully checking the tutorial against what I was doing. Thank you, Skantin, and everyone else.

Ha! I've a feeling that the OP already tried that. I did, to no avail. My overflowing text does not go away. I no longer need it, but when I try to publish, I'm reminded that I have overflow text. If I insert empty frames to let it flow in, one of the results (sometimes, I can't even predict what a result will be because it's not consistent) is that the rest of the document goes blank, all 150+ pages. This was originally a Word document, and it's been a nightmare to put together. Another result is that the text will spill across the entire two pages, inside and outside of the the layout, into the abyss. Yet another is that all the links go haywire and I'm left with cris-crossing links, and I do mean haywire. I've worked through (or around) all of the program's quirks that I've encountered so far, but this one's got me beat (I'm using the latest version.)