Hello there!
One thing I can think of, although this is a bit of a gamble without looking at your logs, is that this could be related to our performance scanning feature. If this feature is used extensively, this could potentially cause a delay in scanning and explain the issue you're facing.
Performance scanning is a feature which can demand a lot of resources from your Lansweeper servers, and as such, we recommend only enabling performance scanning for critical assets such as application servers, database servers, domain controllers, etc. to avoid any performance issues in your Lansweeper installation.
As a test, we would recommend temporarily disabling all your performance scanning targets under Scanning\Performance Scanning in the web console. Once all performance targets are disabled, make sure also to restart the Lansweeper scanning service under Windows services. Trigger your scanning targets or wait for their scanning schedule to kick in, and monitor if the issue persists with your scan items not being updated.