1. Create an issue (in my case, it was of type "Bug report", but this may be irrelevant); "file" it;
2. Open the issue that you just "filed", and click "More actions" -> "Attach file";
3. Either browse to, or drag & drop one or more permitted files; click "Save attachments";
4. Result: toaster gives JavaScript error "Undefined variable: options". The pop-up does not self-dismiss. One has to close the toaster message, close the pop-up (via the "x" button) and refresh the page. After refreshing the page, SOME of the files that were attached do show up in system-generated comments to the respective issue. At least one file did attach in every attempt I made, but I also got two and even three. Note that these were smallish PNG pictures, under ~35K each, so it's something random, but no idea what is.

Observed the bug in "http://maidens.thebuggenie.com/" (I believe hosted accounts always run the latest version). Used a regular user (i.e., not ADMIN user, if that makes any difference).

Chrome Version 72.0.3626.96 (Official Build) (64-bit), running on Windows 10 64bit, version 1803.

Thank you, Claudius