Order of nodes not saving & adding new node overwrites previously added nodes

[robin-braibant-alpine]

I am using Craft 5.1.2 together with the Navigate plugin version 5.1.1. and I have two issues.

I created a navigation for the footer with the possibility to use 2 levels. For example:

Issue 1: When I want to change the order I get the "Order updated" notice, but the order does not get saved. For example: you change the order, wait for the notice and refresh the page, the order will be reset to the previous order.

Issue 2: When I add a node, I also get the notice that the node has been saved, but when I refresh the page another node has been overwritten. Situation After adding node and Before refresh:

Situation After refresh: