Ok, I'm confused...  given the following map & unit set up (standard enhanced unit set - default everything except that air transports move 3 instead of 2):

I find that an army that comes from the city side (116 production) can move right to left, "through" or "over" the producing resource... BUT,  an army on the left of the resource (or either of the engineers in the picture above) cannot move from left to right and get into the city.
In the picture above the army (which was produced in and came from the city) cannot move back into the city.  The game "bonk"s.

To get around this I had the engineers build an airbase and just flew things around the resource (because I could find no way to deactivate/abandon/delete a developed resource), but it was really strange and seems totally bizarre...  I would expect identical behaviour in either direction. 

Am I missing something here?  As best I can tell there are no "hidden" units anywhere.

Please let me know if any other info is needed and/or appropriate.... or if there really *is* a way to abandon/delete a producing resource.

Thanks,
Gary

  running on Ubuntu 16.04LTS.

You need to create a road to the left of the oil well.  The reason armies can get out is because building the oil well also creates a road underneath the well.  That allows units to stack in the space.  But when attempting to return the units would be moving from a square with no road (rough terrain I assume) onto a partially occupied square (the oil well).

Basically, when I have the choice I do not like to build oil wells in the line of travel of my armies as they do tend to create bottlenecks like this.

When I create scenarios I really try to make sure that these sorts of resource placements are not present.

Hope that helps.

Cheers :)

Ah... I noticed that the "ends" of roads are a tad strange, but that's still bizarre.  The terrain underneath the various pieces is/was as follows:

    ~~~~~          ~~~~~~~            ~~~~~~

    forest        river+resource         city

     clear             ~~~~~~~           ~~~~~~

So what you're saying is that an army that can normally  move over anything but a peak, cannot enter a road/resource from a forest even though it would normally be able to move from a forest to a river if the road/resource wasn't there.

This bears out as I ended up building an air base on the clear terrain - something that has an 'implied road.  After that the army could move from the forest to the air base and then into the resource.  This raises the question of why a transition from forest => air base (implied road) is different than the transition from forest => resource (implied road).  First one is OK, second one isn't.

As an experiment I disbanded the air base and attempted to move from the clear into the river+resource... and still couldn't... so, (having disbanded the air base that used to be on the clear, I built a road segment there... and then the units could move into the river+resource without problem.  I have to consider this strange behaviour because I've never had trouble leaving or entering a road somewhere in the middle of it -- although I learned that you have to start/end a road on terrain that the unit is actually capable of moving on... but in this case, road or no road, hidden or not, the units should have been able to move on that terrain.

One could become EXTREMELY frustrated with this sort of hidden behaviour.

Is this road or resource beginning/ending behaviour documented anywhere?  I've read the manual more than once (but don't have it memorized!  :-)

Thank you, very much for this explanation!

Sincerely,

Gary

PS: Interestingly enough I found a very similar situation at another place in the game where an army that I'd directed to go from A to B (about a distance of 15 - mostly clear terrain - was still trying to get through a choke point that was blocked by a developed resource.  It would continually oscillate back and forth trying to get through.  I discovered it some 100 moves later after wondering why it hadn't reached it's destination yet.

I cannot answer your question about why this happens, I can only speculate.

I think the game reads a resource square as occupied somehow, and when you try to enter from any any terrain other than a road it blocks that movement due to the "occupation."

As roads allow stacking of units, going from road to road with resource over it does not have the issue.

Only speculation though, Mark as the designer would have to comment.  As you say, I don't think this is covered in the manual.

Cheers :)