I use #exit#entry anchors to position components. But everytime I restart Glyphs I have to select first component, right-click and Disable Automatic Alignment, and then again, right-click and Enable Automatic Alignment to make it work correctly. I need to set sidebearing, not inherit form components.
Looking into it today, sorry, didn’t find the time over the weekend.
[UPDATE/EDIT]
I had a look now, and the glyph behaves as expected in my installation, Version 2.4.1 (971). The lowercase u has the LSB of upper_serif and the RSB of a_ending, the last component in the chain.
(What I am not so sure about is whether exit and entry anchors are the ideal solution for this kind of setup, but don’t let that keep you from experimenting with the technology, please.)