What Absolute tolerance in Properties > Units are you using? If it is 0.00001 change it to a more reasonable value such as 0.01 or 0.001.

To create a solid using OffsetSrf with Solid=No on a collection of surfaces some of the surfaces will need to be extended or trimmed in separate operations.

I would be extremely surprised if OffsetSrf with Solid=Yes produces results when it does not produce results with Solid=No for the **exact** same surface or polysurface.

To obtain a single solid in one step using OffsetSrf with Solid=Yes you need to start with a single surface or polysurface as input. Using multiple surfaces and/or polysurfaces as input results in multiple solids, one per input surface/polysurface . The results may appear as a single solid, particularly when viewed in Shaded mode, but there will be a distinct solid for each individual surface/polysurface.

Also look at your results using Wireframe as well as Shaded. Wireframe can take a bit of practice to understand but sometimes shows aspects of the geometry which are hidden in Shaded.

A strategy to create offset surfaces and solids from complicated geometry is to break the geometry down into several simpler parts, such as the hull, each strut, etc, and create a solid from each. Then merge the solids together; sometimes this be can done with Boolean commands only but frequently some “manual” work with Intersect, Trim, Split, ExtendSrf, and Join is also needed.

You may want to set your current project with it’s complexities aside temporarily and work with a simpler shape to learn about solving geometry problems and offsetting surfaces. Then after success with the simpler shape go back to your more complex project and complete it successfully.