Unable to edit server side rendered block

Question

You’ve gone with a class based component and the normal solution for this problem is that you forgot to use useBlockProps.

Your edit component and save components do not use useBlockProps:

    edit: ( props ) => {
        return <ServerSideRender block="wp-portfolio-manager/wppm-block"></ServerSideRender>;
    },
    save: (props) => {
        return null;
    }

Wrap your server side render component in a div and apply useBlockProps to that div and the problem should go away.

Something similar to this:

<div { ...useBlockProps() }>
    ... etc
</div>

useBlockProps gives the opportunity for the block editor to inject event handlers and extra CSS classes. This is how it styles the selected block and handles the selection process, as well as things like animating block movers etc.

Also, be wary of class based components. WP hook APIs such as useBlockProps don’t work with class based components. Everything you are doing here can be done with useState and useEffect, though it looks like none of your class based components are actually in use.