I think I got it! Thank you very much for the screen recording, but thank you to Wes too for the observation about the last shape being auto-selected, which has been the key to realize what could be going on there just when I was about to desist, even though I was quite intrigued about all this... Well, it seems you have the
Points-Based Selection checked, isn't you? And since when working with such tools last points drawn get selected, for the nature of such feature the corresponding shape is selected right away, which interferes on the process of getting next shape properties like stroke width and so. Well, I hope I can now workaround it somehow and that's what I'm going to try to do right now, but in the meantime you can turn off the (in my defense, experimental

)
Points-Based Selection setting and the problem should go away.
BUT NOT ONLY THAT! Thanks to I installed the previous version for testing this, I have realized also that it didn't present the deleting keyframes problem, which I started to take for granted it could be something beyond my possibilities to get fixed, but this find means the problem is indeed in my side and I can make something about it, super good news!

Even though I'm afraid it will have something to do with the shape preview widget and I hope I can find the way to fix it while maintaining it...
Well, what can I say, thanks to you for the amazing contribution
EDIT: 
Even
gooder news... It appears already fixed to me in (the not yet released) BETA 0.2.1, I guess as a side-effect of having solved a copy/paste buttons kind of related issue... Anyway, greater! Since that means I can pass to investigate the deleting keyframes issue right away. BTW, the plan is that as soon as I get it fixed too (I hope), make available the new build as soon as possible, contrary to what has been usual... Cheers!
...