Do These in order:
1. Clear Cache [Go to Dashboard > Systems & Settings > Optimisation > Clear Cache]
2. Clear Browser Cache follow this link
3. For Add-ons, create a test page and make sure there are no other blocks existing in that page other than the Add-on you are troubleshooting. Also make sure that the test page is using a default theme either Plain Yogurt or Greek Yogurt theme. Now, try adding the Add-on in any of the areas within the test page and see if the issue occurs. If not, most likely there are other factors that causes the malfunction. To investigate further go back to the original page where you are experiencing the problem and troubleshoot further:
- If the original page is using a different theme other than Plain or Greek Yogurt try changing your theme to either of these default themes.
- If the error is gone then most likely the problem is caused by your theme.
- Otherwise, proceed to the next step.
- Return to your original theme and disable or remove the other blocks that exist in the same page you are working on one by one. Make sure when you remove the blocks, test the add-on you are troubleshooting and identify at which point the add-on works. It is most likely that the block that you have just removed is the causing the conflict.
- If you do not want to follow the previous step especially if you have a lot of blocks installed, try doing the other way around. Instead of removing the blocks create another test page and replicate the blocks that exist in the page where you are encountering the problem. So this time instead of removing the blocks you are adding the blocks one by one and make sure to test the add-on that you are troubleshooting and determine at which point (when adding the blocks) does the problem occur.
4. If the problem still cannot be identified with 1-3 reinstall an Add-on to make sure the files are loaded properly. Here's a link on how to manually download and install an add-on.
5. If none of the above helped you identify the problem just send us a support ticket and we will look at the ticket asap.