Can't unhide text-field blocked text on Mac

[Alliterator]

As part of my teaching, I've created a case study on my PC with questions and answers, whereby the answers are hidden using a combination of text-field blocking (i.e. creating a text-field over the content and filling the text field in with colour) and the button (with the "Show/hide field" action). However, when I sent the file to a fellow teacher, who is a Mac user, she was unable to activate the button to "hide" the text-field, thereby revealing the answer. 

Have we missed something? Are we doing something wrong? She tried Adobe and the Mac .pdf reader to no avail.  

[try67]

What app did they use to open the file? If Preview, that would explain it. Instruct them to only use Adobe Reader.

[Alliterator]

They originally used the Mac-default pdf reader, which didn't work, but I then told them to use Adobe Reader (not Pro) and it still didn't work. I can post up the document itself and see if anyone else has issues with it.

[Bernd Alheit]

What does you use at the button?

[Alliterator]

I use "on focus" and "show/hide field". Is that what you're asking?

[Bernd Alheit]

Can you share the document?

[Alliterator]

https://1drv.ms/b/s!AlGgLcbqnFv0gb0ac46hlqz5NN8JeQ?e=LtOOvI 

Let me know if you can't download the file. Thanks for the help!

[Bernd Alheit]

It works in Acrobat Reader DC.

[Alliterator]

1. Can I assume that you're using a Mac? If so, then do you have a suggestion as to why it wouldn't work on my co-worker's Mac?

2. Is there a difference between Adobe Reader and Adobe Reader DC?

[Bernd Alheit]

1. The co-worker should use Acrobat Reader DC

2. No. DC is only the version.

[Alliterator]

I checked and she's definitely using Adobe and it still isn't working.

Is there another way I achieve the same effect i.e. hiding answers and having a mechanism that can reveal the answer?

[Bernd Alheit]

You can try as trigger "Mouse Up".