Can't add more vertices to convex region after creating a line of vertices.

Server Implementation

Paper

Server Version

1.16.5

Describe the bug

When adding vertices to a convex region, if you add them in a line no other vertices will be added.

To Reproduce

Start a convex region selection.
Add a vertex to the left.
Add a vertex to the right.
Try to add more vertices somewhere else (Part that doesn't work).

Expected behaviour

To add extra vertices.

Screenshots / Videos

https://user-images.githubusercontent.com/32806171/143670759-d7e2ff4d-fa56-4708-b5ea-f3651e390588.mp4

Error log (if applicable)

No response

Fawe Debugpaste

https://athion.net/ISPaster/paste/view/d477662482ef4101bb7031617300be0e

Fawe Version

1.17-409;11e2591

Checklist

• I have included a Fawe debugpaste.
• I am using the newest build from https://ci.athion.net/job/FastAsyncWorldEdit-1.17/ and the issue still persists.

Anything else?

Still present using only FAWE.
https://athion.net/ISPaster/paste/view/9e4d04e142b140e28755125c10fc14d8

Using the API to make a convex region then manually adding the points makes them appear using region.getVertices(), however, when trying to actually edit the region, only the original line of vertices is changed.

Reproduce the convex region selection described in the issue, including the API case where points are added through region.getVertices(). Start by tracing the convex-region selection and editing paths. Done means vertices added after a straight line are accepted and the resulting region edit includes them.