To place a survey point marker on a line string, Trimble Business Center uses symbols located in a symbol font file, symbol.shx. If this font file is placed into the AutoCAD (or other CAD) fonts folder (e.g C:\Program Files\Autodesk\AutoCAD 2018\Fonts) then a drawing exported to CAD format will display as expected. However if the font file is missing, the survey point markers on a string will appear as other types of symbol.
An alternative to copying the symbol.shx file to the font folder is to convert the point markers to blocks using AutoCAD, before issuing the drawing file to a 3rd party. The procedure shown in this video (on link) shows how to make this conversion using a LISP script.