Hello,
We can see the table loading now - but, this is an SQL based table, so if you use server-side processing enabled in the table settings, and if you have any kind of active caching on this Page, in some instances, it can happen to get an "invalid JSON"/or AJAX error.

Here are more details and how you can fix it :

We currently have this issue which only happens for server-side processing tables when you have caching active on the page.

Our developers are intensively working to resolve this issue, as soon as possible. I can't say an ETA on it, unfortunately.

You can certainly follow our changeLog page if you'd like ( it is also available in the plugin dashboard), where we state any changes/new features/bug fixes during updates;

and our newsletter, so you're informed about new features, bug fixes, freebies, etc.

For the time being, the only two possible solutions will be:

1.  To disable caching only for pages where you have the tables, or perhaps disable caching entirely, if possible.

Most caching Plugins have the option to add URL's that will be excluded, so if possible, see if you can add the Pages with tables there, and that should solve it for now.

2. Or you can try disabling the server-side processing option in your Table.

For the Manual Tables, it is not possible to disable server-side processing,

but you can make a new SQL Query based table from the same data which is stored in a Manual Table.

This is how that is done.

First, check what is the MySQL Table name inside the Editing settings,

then make an SQL Query like : 

 SELECT * FROM TableName  

For any SQL Query based Table which has less than 2 thousand rows, you can disable the server-side option on SQL tables, and it will work like it does for tables linked from files. ( loads all rows on the browser regardless of table's pagination)

If you need to increase the row count while still having the "toggle" to disable server-side,

Please go to ../wp-content/plugins/wpdatatables/source/class.wpdatatable.php and around line 3188 you'll see this:

if (is_array($res_dataRows) && count($res_dataRows) > 2000) {

The lines of code can change during Updates because our Developers add new lines from time to time, so it is best to search for the line in any Code Editor with CTRL+F to get the right line.

You can change the number 2000 to a value bigger than the number of rows in your table in order to still have that 'toggle option' for server-side processing.

Another PHP file in this path :

../wp-content/plugins/wpdatatables/source/class.wdtconfigcontroller.php

In this file, please search for this, there should be two occurrences, first one around line 82 as :

if (count($wpDataTable->getDataRows()) > 2000) {

And second one around line 143:

if (count($wpDataTable->getDataRows()) > 2000) {

That will increase the server-side processing option automatic limit.

We just advise caution not to increase that number 'too high' to avoid going over the limit what your Hosting Server's PHP Limitations can handle.

Usually, up to around 5 to 6 thousand rows should pose no significant performance issues, but if you go higher than that data size without server-side processing, you could experience slow loading times.

You can certainly test to see how a Table behaves on front-end, and if it loads too slow/or freezes the browser's Page, you can go back in the Table's Back-End and enable server-side processing for that Table.

Let us know how it goes and if you have any questions.

Thank you.