SQL and Explain sometimes not visible in query monitor - response (1) by gryback

Visibility of SQL and Explain plans in Viewpoint have a number of dependencies which you have alluded to above. Let me provide a high level explanation for everyone's benefit.
 
The "Session Sampling" which is set in Admin -> Monitor Rates defines how often Teradata DB collects information to support the API interface. The Admin -> Teradata Systems -> Data Collectors collection rate informs Viewpoint how often to pull data from Teradata. As such, the collections rate should not be more often than sampling otherwise you will be unnecssarily pulling duplicate data. 
 
The SQL and Explain thresholds qualifies queries for SQL and Explain collection. If a query doesn't exceed one of those two thresholds, for efficiency, the SQL and Explain is not collected into Viewpoint. 
 
So Duri, your configuration appears to be set to best practices allowing necessary but also efficient SQL and Explain collections. You should be able to verify in Query Monitor based on the "CPU Use" and "Duration" columns. If either of these columns has a value greater than your SQL and Explain thresholds, you should be seeing that information on drill down details.