Core's views module attaches two insert command, one of them is "prepend" that causes empty text overwriting the output if the prepend is replaced by viewsShowMore.
ViewAjaxController::ajaxView
$response->addCommand(new ReplaceCommand(".js-view-dom-id-$dom_id", $preview));
$response->addCommand(new PrependCommand(".js-view-dom-id-$dom_id", ['#type' => 'status_messages']));
This causes contents are missing after click the view show more button.
Just regular view with more than two pages contents output.
Update ShowMoreEventSubscriber:
if ($command['command'] == 'insert' && $command['method'] == 'replaceWith')
.Probably not the best solution but additional defensive code to make it more robust.
Fixed
2.0
Code
This fixed an issue that I was having where the JS code was called twice after clicking show more.
Automatically closed - issue fixed for 2 weeks with no activity.