Recently, I noticed that issue and comment previews are not rendering Markdown properly. This used to work perfectly, but now it appears that newlines in the input are being ignored. As such, everything is getting processed as a single line, which breaks many formatting features:
For reference, I am running Microsoft Edge (42.17134.1.0) on Windows 10 Pro 64-bit, 1803 (17134.48). This occurs with no extensions loaded.