Before submitting a bug report i would like to find out if you perhaps already have a bug report regarding this issue.
I searched answerhub but could not locate anything. Perhaps my wording is incorrect.
When you collapsed a section of the blueprint to a node, and it contains Do Once nodes… and you change the input of that section, all Do Once nodes inside of it is corrupted throwing errors and they are all then referencing the input nodes of the collapsed graph.
The result is you need to duplicate all those nodes, and rewire them.