Cube glitch in test chamber 19

[Bees]

I'm up to the part that you need to get the rocket launcher to blow up the cube tube. The cube drops out, but it falls through the floor. I caught it once before it fell, but when I try to put it down it just sort of rolls around and then drops through and I can't get on top. Is there anyway to fix this?

[canci3]

I am faced with the same issue. I grabbed the cube falling from the delivery tube. But I cannot put it down, it will just fall through the floor. :(

[The Man Who Told The World]

I'm sufferng the same glitchy fate. Did anybody get a fix for this?

[AeX10]

Don't catch it, let it fall out of the tube doesn't glich for me

[~[United Porters]~]

This happened to me as well, playing through again with my kid. Tried multiple times just letting it drop. It would disappear through the floor. Got smart and was able to catch it midair as it dropped out of the tube, only to have it fall through the floor as I put it down near the vent. Ultimately had to turn on noclip to get through up to the vent.
The big disappointment came as we started to fight Glados, as the cores fell through the floor too. We ended up just watching the finale on Youtube.

[Fatmeatball]

Strange, it doesn't happen to me.
Try reinstalling the game or verifying the cache.
(Don't worry, your progress is still there even if you reinstall it.)

[Hermes Passer]

This happened to me too.

[Doko]

Happened to me too, still not solved 6 years later :-(

[至尊宝]

Happened to me too, still not solved 6 years later :-(

[Calmly Frenetic]

You may have accidentally activated the "item save glitch" at a previous point. You will need to load a save from before it happened, or in the worst case start a New Game at the last chapter.

[DEFOLZ]

Where is portal 3

[Bystander]

Bug still exists in October 2020 :(

[Fearless]

it stil happens?

[Nekogaming1500]

Not for me. It just hit me on my skull.

[Senayna]

It still happens, yes. Couldn't finish my game either. Tried it with loading an older save point, still the same issue. Therefore I quitted at this point and watched the end on Youtube. A bit disappointing, but well... better than never seeing the end.

[.floggy]

same problem exists in 2021, its sad.