Rated 5 out of 5 stars
Installed 8.5.2 and the attachment reminder problem is fixed, both immediate send (through Send Later) and delayed send. Thanks! Bumping it back up to 5 stars.This review is for a previous version of the add-on (8.4.5).
This should be fixed in the upcoming release, which will be available here later this week. In the mean time you can install it manually from the project's github page: https://github.com/Extended-Thunder/send-later/releases
Let me know once you're on that version if you're still having this problem.