I’m not 100% sure, but I think the following steps will reproduce the issue:
- Start writing a new post
- Add some text with
[spoiler]tags around it. - Unblur the text in the post preview. Note that you can reblur and unblur it as much as you want.
- Add some more text underneath the spoilered text.
- If you left the text in a blurred state, but you unblur it once. But after that (or right away if it was already unblurred) you cannot reblur the text again.
This can also happen in actual posts, not just in post previews. I’m not sure the exact steps to reproduce there (since you can’t type more between unblurring and reblurring), but as least in the one situation I saw the issue for, the blurred text was within details tags. I have no idea if that’s relevant though.
The following is for testing, but may or may not be helpful.
Some spoiler text
Some text after spoiler text.
Summary
Some more spoiler text
Some more text after spoiler text.
Some more text after spoiler text and details tag.
