Isolation question

[ComradeP]

No problem. After 9 years of playing PzC, I'm also still discovering situations I don't fully understand. The mechanics are easy to understand, until a point where you don't understand them when applied to a particular situation.

As to engineers and supplies moving across a river, from the manual:

Engineer Ferry Operations

When an engineer capable of ferrying units across a river exists, then supply can be traced across a river one hex if necessary, to supply units that would otherwise be Isolated on the other side. The supply resulting from this only extends a distance of one hex from the engineer unit across the river hex side.

This prevents units being ferried across a river immediately being Isolated the next turn. It also causes situations like the one you posted. Engineers using Bridge Operations can't supply units across a river using this rule (as they're incapable of ferrying units when doing so, a prerequisite for this supply rule).