I made a couple of Potions of Harming (Instant Damage II), normally I can add a gunpowder to this through the brewing stand for Splash versions of these.
Now I can't even place these Potions of Harming II in to the brewing stand. So am not able to add the gunpowder.
The other way around is still possible, making a Splash Potion of Harming I into a Splash Potion of Harming II by adding a glowstone dust to it.
Thank you for your report!
We're actually already tracking this issue at MCPE-86636, so I will resolve and link this ticket as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – ✍️ Feedback and Suggestions – 📖 Game Wiki