Aircraft can get stuck parking on stand if saved at the end of the parking sequence

3 GA Aircraft are stuck and cant be removed from their stand.(The three facing north on the screen grab). I have tried dismissing aircraft, closing stand and demolishing stand; dismiss does nothing and the other two wont work because there is an aircraft on it.

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COLLECTED HARDWARE DATA
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Device
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Model: MacBookPro14,3

Operating system: Mac OS X 10.13.6

RAM size: 16 GB

Battery status: Full
Battery level: 1

Processor Device
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Type: Intel(R) Core(TM) i7-7920HQ CPU @ 3.10GHz
Core count: 8
Frequency: 3 GHz

Grahpics Device
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Vendor: Apple
Type: AMD Radeon Pro 560
Memory Size: 4 GB

Screen Summary
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Full Screen: True
Resolution: 3360 x 2100 @ 60Hz