The latest update to AI has caused this issue. When exporting an svg with dashed lines, the svg's dashed lines either disappear or become dotted lines.

Operating System: Windows 10 Enterprise
Adobe Illustrator version: 27.0
Steps:
1) Open Adobe Illustrator
2) Create a new file
3) Draw a line
4) Open the properties window by going to Window > Properties
5) Click on the Stroke option
6) Check "Dashed Line" on
7) Set the first "dash" to 10
8) Make sure the rest of the "gap" and "dash" options are blank
9) Go to File > Export > Export As
10) Make sure the "Save as type" option is SVG
11) Click Export button
12) Set Stylng to Inline Style
13) Set Font to SVG
14) Set Images to Embed
15) Set Object IDs to Unique
16) Set Decimal to 5
17) Keep Minify off and Responsive on
18) Click OK

If you open the SVG in the text editor, you'll notice "stroke-dasharray: 0 10;" in the styling of the line. It should say "stroke-dasharray: 10;" Unfortunately, it won't let me upload any sample files.

Thanks,
Vince