I’m on Ubuntu Linux 16.04, this happens both in Firefox 49 and Chrome Version 53.0.2785.116 (64-bit). I could do all of this earlier this week, so it seems like a regression.
Where are you and what language is your keyboard set for? Do you use a comma as a decimal separator? Try using semi colon ( instead of comma ( ,) as the separator between the dimensions. And what happens if you omit the quote mark ( " ) ?
I’m in Belgium and use the English (international AltGr dead keys) keyboard layout (hardware is a qwerty keyboard). This is a Linux-only layout I think.
I experimented some more, and things go wrong the moment I use the double quote character: ". I’m able to enter feet (so ') without an issue.
I wouldn’t be using feet and inches if it wasn’t for the tutorial though, I use the metric system natively and that does works.
(to clarify: a different separator doesn’t matter, things go wrong before the separator)
When you type a decimal number would you use
1.234 or 1,234
I think in Belgium you’d use the comma rather than the full-stop [aka ‘period’ in the USA] as the decimal point.
As Dave says the convention in the USA,UK etc is
1.234,5.678
where the separator of the two number is a comma, since the numbers contain a full-stop.
In most of Europe it’s
1,234;5,678
where the separator of the two numbers is a semi-colon, to allow the use of the comma in the number.
Also be aware that on PCs with an extended keyboard SketchUp does not read the full-stop on the number-pad as a comma if the user’s locale expects it, you must use the comma on the main key-set.