Look in your ACP, it should tell you if any errors have been logged.
For the browser, open the console first,
- from the menu: select "Browser Console" from the Web Developer submenu in the Firefox Menu (or Tools menu if you display the menu bar or are on OS X)
- from the keyboard: press Ctrl+Shift+J (or Cmd+Shift+J on a Mac).
Then try uploading a image, see if any errors are shown.
This is what in broswer console:
<source> element has no “src” attribute. Media resource load failed. watch
All candidate resources failed to load. Media load paused. watch
Attempt to set a forbidden header was denied: Connection 1339977637-lcs_client_bin.js:193:386
cas.pxl.ace.advertising.com : server does not support RFC 5746, see CVE-2009-3555 (unknown)
The character encoding of the plain text document was not declared. The document will render with garbled text in some browser configurations if the document contains characters from outside the US-ASCII range. The character encoding of the file needs to be declared in the transfer protocol or file needs to use a byte order mark as an encoding signature. edge.4.0.1.min.js
The character encoding of a framed document was not declared. The document may appear different if viewed without the document framing it. MUFG_OLA_300x250_edge.js
The character encoding of a framed document was not declared. The document may appear different if viewed without the document framing it. MUFG_OLA_300x250_edgeActions.js
Using //@ to indicate sourceMappingURL pragmas is deprecated. Use //# instead jquery.min.js:1
Attempt to set a forbidden header was denied: Connection 1339977637-lcs_client_bin.js:193:386
lyr.pubmatic.com : server does not support RFC 5746, see CVE-2009-3555 (unknown)
Use of Mutation Events is deprecated. Use MutationObserver instead. ca:240:61
Attempt to set a forbidden header was denied: Connection 1339977637-lcs_client_bin.js:193:386