Finding the closest point on multiple surfaces

Hi all.
I want to do the point closest to the surface. However, since my surfaces are made up of parts, when I import them as multi-surfaces, the process does not give the desired result. Merging surfaces doesn’t work. What can I do ?

Post your Grasshopper file with the relevant geometry internalised.

Testing 3dm Archive: C:\Users\martinsiegrist\Downloads\Untitled.3dm
Start Section: 463 bytes (offset 0 to 463)
Offset: 0
3dm archive version: 70
Interface Name: Rhinoceros 7.15 - Corporate, build 2022-02-08 - (compiled Feb 8 2022)

Your license appears to be cracked.