> Previous beta does it right.

Over here I seem to get the same behavior in both the previous beta and the new one.

This seems to be running into a bug that I've seen a few times - trim is actually cutting the cylinder parts, but it gets confused about which parts are supposed to be separated from each other, so the part of trim where you pick parts to delete doesn't work.

You can still trim the object though, instead of picking which part to delete, just push "Done" (or right click in the viewport) right there to just take the result, which is cut but still joined together. Now you can select the faces you want to remove and push delete to throw them out.

When you select the faces to delete, you may need to zoom in a bit to pick the first face, because you need to grab it somewhere that is not nearby an edge since edges take preference. Once you have clicked on one face, you can then use window select to grab the other ones. I think in this case you will want to window select from the right towards the left, that will have a dahsed outline and will grab anything that intersects the window. If you go from left towards the right, it will have a solid outline and only grab things that are completely enclosed within the window.

Please let me know if any of this doesn't make sense.

- Michael