Confusing title, yes, but it's hard to come up with something better that fits. Anyways.
There's a feature in the game, where if there are both construction and deconstruction jobs involving the same resource, trucks can save time by ferrying direct from deconstruction to construction. That's a great feature, and I like it- but it has a problem. Specifically, if the construction job is unreachable, the trucks will not engage in the deconstruction job, even when there are storages available for the components.
Reproduction is... inconsistent. I usually notice this issue when ordering removal of structures that are blocking access to a relatively large number of associated construction tasks. Workaround is easy, at least- just Unity-demolish. Or pause the construction tasks if Unity is scarce.
First encountered... a very long time ago. Currently seen in Update 4.2 | v0.8.6c (b612).