I tried to use the /fill command in the nether replacing air and for a large area the game did not recognise it as air. In the picture you can see what I typed. It targetted everything around the vine, but did not actually fill it, the only bit that did get filled was a bit I had tested on by putting in blocks myself and replace those with air.
It did not work for other blocks either, as if the air was not recognised as such by the command.
Linked issues
Attachments
Comments

I was unaware of that being a thing. I just tried it and it did fill up the blocks that did not fill when replacing just regular air.

Thank you for your report!
However, we are already tracking this issue, and this report is a Duplicate of MC-125135, which is a report that has not been resolved yet.
If you want, you can upvote the parent ticket, and enable watching to receive any updates about it - if you believe you have any information that may be important for this issue, please leave a comment on the parent.
Quick Links:
📓 Issue Guidelines – 🛠 Community Support – 📧 Customer Support – ✍️ Feedback and Suggestions – 📖 Game Wiki
💬 Mojira Subreddit – 💬 Mojira Discord
Have you tried
cave_air
as well?