Hello,
I noticed exactly the same issue, was wondering if it was related to our hosting settings, but apparently not.
I observed that bug indeed with Firefox 69.0 and ACF 5.8.x versions. First thought it was related to a bug in ACF 5.8.4, but apparently it’s not the case.
Also, the issue doesn’t occur with some websites, even with FF 69.0. The problem never occurs with Google Chrome or FF 68.0.2.
When looking at the source code, the correct field type is “selected”, so I’m wondering if it could not be related to some auto-complete feature of Firefox which goes over ?
I wrote a ticket to ACF team to know if they could have an idea.
