In the resource pack menu, the arrows to change the order of selected resource packs do not appear. The arrow to deselect resource packs does appear, but clicking it does nothing.
Selecting resource packs that weren't previously selected works as it did in previous snapshots and 1.13.
Extra notable information: I have an incompatible resource pack with a version number of 18. Changing the version number of the resource pack to 4 and removing it from Incompatible Resource Packs in options.txt <did/did not> fix the issue.
Resource packs can still be disabled by closing MC and editing options.txt, as expected.
My video was too long to upload, so here's a link to it:
https://www.youtube.com/watch?v=V_xmD5uoNJs&feature=youtu.be
Duplicate of MC-146777