I was using command blocks in creative, switched to survival to test lingering potion NBT. When I switched back to creative I couldn't enter any command blocks.

I was testing AreaEffectCloud NBT with impulse command blocks. I would summon an AreaEffectCloud with custom NBT.
1. For my testing, I only changed the NBT radius, radius per tick, particle, and effect.
2. I went into survival to test out the effect.
3. I summoned the potion,
4. walked into the cloud (Wither lvl 6),
5. died,
6. switched back to creative,
and I could no longer edit command blocks.

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
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