Seeking an understanding about migrating Application Insights to Log Analytics Workspace

An update. I ran a number of experiments to test the migration procedure from the classic App-Insights to the new Log Analytics Workspace way of doing things. Within a Sandbox environment I created the classic App-Insights resource, fed logs into it, performed the migration, and then fed more logs. Repeatedly, after the migration was performed there were a considerable number of logs missing from the new Workspace. Feeding brand new logs into the system, the new log entries would all appear in the classic environment but only 25% of the logs would show in the new Workspace. I ran this test multiple times to confirm the results (completely setting up a new environment every time).

We then created a brand new Azure subscription specifically to test this. Within this brand new subscription we encountered exactly the same problem again - after the migration was performed 75% of all new logs did NOT appear in the new Log Analytics Workspace, while still showing up in the classic environment. There was no clear pattern which log entries were missing (such as only info logs were missing while errors were present). It was a blanket loss of 75% of all log data. I created a support ticket with Microsoft to get help as I had run out of options. Despite the SLA saying they'd respond within 4 hours it's been nearly a week now with no response from Microsoft.

However, I discovered something else. After a few days the new Log Analytics Workspace environment appears to begin working correctly. I'm now able to feed new logs in and can see those new log entries appear in the new Workspace 100% matching the classic environment. Could it be that this problem only exists for new log entries? How long does it take before it "warms up" and functions properly after a migration is performed? I hate not being able to explain the missing log entries even if it eventually functions.

Jonathan