Assets App.

I've isolated this issue to Chrome Version 36.0.1985.125.

The button does appear as expected in Safari version 7.0.5 and Firefox 30.

I tried to clear cache on Chrome to no effect. I then completely cleared all files, closed Chrome and opened the browser again. Unfortunately still no effect.

I looked in Chrome console and saw these two error messages

Refused to execute script from 'https://www.environment.ucla.edu/perch/core/inc/js_lang.php' because its MIME type ('application/json') is not executable, and strict MIME type checking is enabled.

Refused to execute script from 'https://www.environment.ucla.edu/perch/core/inc/js_privs.php' because its MIME type ('application/json') is not executable, and strict MIME type checking is enabled.

Addendum

I funneled both through Assets and through upload image on a page template and the script error showed up in both places.

I think I found the cause of the problem.

In my .htaccess file I had this bit of code

 <IfModule mod_headers.c>
     Header set X-Content-Type-Options "nosniff"
 </IfModule>

When I removed it, the problem was fixed. And the two error Console errors also aren't showing up.

Here was the info in my .htaccess file.

# ------------------------------------------------------------------------------
# | Reducing MIME-type security risks                                          |
# ------------------------------------------------------------------------------

# Prevent some browsers from MIME-sniffing the response.

# This reduces exposure to drive-by download attacks and should be enable
# especially if the web server is serving user uploaded content, content
# that could potentially be treated by the browser as executable.

# https://blogs.msdn.com/b/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx
# https://msdn.microsoft.com/en-us/library/ie/gg622941.aspx
# https://mimesniff.spec.whatwg.org/

 <IfModule mod_headers.c>
     Header set X-Content-Type-Options "nosniff"
 </IfModule>

Maybe a conflict with something else in .htaccess?

 <IfModule mod_headers.c>
     #                           (1)    (2)
     Header set X-XSS-Protection "1; mode=block"
     <FilesMatch "\.(appcache|atom|crx|css|cur|eot|f4[abpv]|flv|gif|htc|ico|jpe?g|js|json(ld)?|m4[av]|manifest|map|mp4|oex|og[agv]|opus|otf|pdf|png|rdf|rss|safariextz|svgz?|swf|tt[cf]|vcf|vtt|webapp|web[mp]|woff|xml|xpi)$">
         Header unset X-XSS-Protection
     </FilesMatch>
 </IfModule>

Or (doubtful)

<FilesMatch "(^#.*#|\.(bak|config|dist|fla|in[ci]|log|psd|sh|sql|sw[op])|~)$">

    # Apache < 2.3
    <IfModule !mod_authz_core.c>
        Order allow,deny
        Deny from all
        Satisfy All
    </IfModule>

</FilesMatch>

Or gzip (doubtful)

AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript

No on gzip. Yes, on XSS, yes on nosniff,

Plenty of HTML 5 boilerplate is not used.

Back to sleep for me in LA, and I need to run some more tests during day.

Plus side — commenting out nosniff worked.

Thanks Drew.

Whinging is a new word in my vocabulary.

Quick dummy check. Will your change will be rolled into the next update?