After updating to Spigot 1.18, chunks visited by player disappear on Dynmap

Issue Description: Today I updated to Spigot 1.18. I also updated to the latest stable version of Dynmap on this page. Now, when players log in and visit locations that have been previously correctly rendered on the Dynmap, those chunks disappear. Fullrender also makes the map start to disappear.

Here’s chunks vanishing as a player visits them:

Here’s a fullrender from spawnpoint in progress: (Here it is on our Dynmap)

• Dynmap Version: 3.3-SNAPSHOT-567
• Server Version: [23:52:14] [Server thread/INFO]: This server is running CraftBukkit version 3336-Spigot-a5dea1c-a008701 (MC: 1.18) (Implementing API version 1.18-R0.1-SNAPSHOT)
• Pastebin of Configuration.txt: https://pastebin.com/6KrkLFsT
• Server Host (if applicable): Nitrous Networks
• Pastebin of crashlogs or other relevant logs: Nothing relevant in logs
• Other Relevant Data/Screenshots: Recently updated Spigot server, from 1.17.1 to 1.18. Here’s our Dynmap.
• Steps to Replicate: There’s two situations:

1. Log in after updating to 1.18. Go to previously rendered area of the map. Map rendering vanishes online.
2. Update to Spigot 1.18. Run /dynmap fullrender world. Tiles that would usually render anew or more accurately are replaced by black squares.

[I’ve done my best but the issue titles and descriptions are not average-user-friendly] I have looked at all other issues and this is not a duplicate
[x] I have been able to replicate this

[mikeprimm]

OK - I’m seeing this with current DEV build, but not with the released 3.3-beta-1, so I’d suggest using that for now (since it is, well, released…) DEV (SNAPSHOT) build go from working to not on a regular basis while I’m doing development, so its generally not safe to count on them unless I specifically say they are ready to be used…

[CardLin]

Now, the problem is clear. The border between new chunk(1.18.1) and old chunk(1.17.1): Player visted area may update to 1.18.1 chunk. The border is about 180 blocks wide…