Yeah someone else with this problem! When I try to reblog something and add comments after it before posting, anything I write disappears.
I can edit to add the text again (I see some people can’t even do that), but it’s still pretty annoying.
Some good news though. I contacted Support about the issue, and according to them the issue seems to be specific to Firefox. So if you’re using Firefox, there’s your problem. They say they’re aware of the issue and trying to resolve it. So I guess we just have to wait it out or use another browser, if possible.
Not using Firefox? Tell Tumblr about the bug and which browser you’re using: firstname.lastname@example.org.
Edit: Good to know!