Still having this problem but figured out you can save as a png, open a new blank doc in illustrator, drop the png into the new doc, image trace it and play with the settings until its exact and then finally export that as an svg. A real pain but at least theres a few workarounds.

Same type of problem here using newest 2018 Illustrator.
Copy and paste the image into Photoshop and export from SVG there works fine (but this is a major PITA)

I have drawn a simple oval that exports correctly.
I then made 20 copies, and it exports as SVG correctly.
I then made 20 more copies (so I have 40 of these oval shapes) in two columns side-by-side. The first column exports correctly, the second column some of the ovals are longer, some are shorter and the horizonal position shifts back and forth.

Used the Export Selection command. Have tried all different SVG parameters, have tried switching the columns, nothing has worked.

I can't attach any files as this stupid system says that .AI and .SVG files are not allowed.

I have drawn a simple oval that exports correctly.
I then made 20 copies, and it exports as SVG correctly.
I then made 20 more copies (so I have 40 of these oval shapes) in two columns side-by-side. The first column exports correctly, the second column some of the ovals are longer, some are shorter and the horizonal position shifts back and forth.

Used the Export Selection command. Have tried all different SVG parameters, have tried switching the columns, nothing has worked.

I have drawn a simple oval that exports correctly.
I then made 20 copies, and it exports as SVG correctly.
I then made 20 more copies (so I have 40 of these oval shapes) in two columns side-by-side. The first column exports correctly, the second column some of the ovals are longer, some are shorter and the horizonal position shifts back and forth.

Used the Export Selection command. Have tried all different SVG parameters, have tried switching the columns, nothing has worked.
I can't post the AI file (not sure why it's not allowed on this forum, seems dumb) but attached the generated SVG here.

I have drawn a simple oval that exports correctly.
I then made 20 copies, and it exports as SVG correctly.
I then made 20 more copies (so I have 40 of these oval shapes) in two columns side-by-side. The first column exports correctly, the second column some of the ovals are longer, some are shorter and the horizonal position shifts back and forth.

Used the Export Selection command. Have tried all different SVG parameters, have tried switching the columns, nothing has worked.

I'm experiencing same thing- particularly on files that utilize filters. And including many files downloaded from Adobe Stock that are simple icons. Polygonal patterns won't export without an outline around each shape. Layers with varying filters and opacity won't export. We're having to use png files which is not ideal for responsive web design. I shared my files here: https://illustrator.uservoice.com/forums/601447-illustrator-bugs/suggestions/36044137-svg-export-distortion

Hello Ken,

Thanks a lot for reporting the issue you see. Would you be able to share the file that you try to export with us? You may upload the file here directly or get it sent to us: sharewithai@adobe.com.

Thanks a lot in advance!

Greetings,
Dirk