Performance problem resulted starting in 2019.4.2 for some flows with Union.

Flow execution error occurred, "Failure evaluating to database: "hyper_execute_query". Could not execute the given query. The result status code is 7." when multiple data sources unioned to include a live Teradata data source.

Tableau Prep logs rotated based only on timestamp, not size limit.

After launching Tableau Prep on a Mac, the zoom shortcuts "command and +" or "command and -" did not respond for other applications.

When connected to a published data source, invalid calculated fields did not show an error.

Publishing a flow created when Tableau Online was auto signed in on launch sometimes resulted in one of the following errors "All publish steps must publish to the currently connected server "tableau_online_instance" and site "site_name". Update the publish sets then re-publish the flow.
Or
All published data source inputs must be from the same server or site where you publish the flow. Either publish the flow to that server or site or connect to published data sources from the currently connected server "tableau_online_instance" and site "site_name"."

When connected to Snowflake, selecting a database sometimes reset the selected warehouse.

The incorrect schema displayed when switching from "Create table" to "Add data to table" with an existing table.

Searching for RANK() or ROW_NUMBER() in the calculation editor did not provide enough information to help with writing a full calculation.

Filtering 750 or more rows in a Clean step sometimes resulted in the error "System error: java.lang.StackOverflowError"

"Group and Replace" sometimes resulted in the following error "System error: com.tableau.loom.doc.exceptions.LoomIOException: Problem with IO:Failure evaluating to database

hyper_execute_query: 0 collation mismatch, use COLLATE statements to resolve"

Tableau Prep did not always return the expected number of custom split columns when the number of splits needed varied greatly across rows.

New option to Preview data based on refresh type (Full or Incremental) to accommodate new, potentially different, write options users can specify, is non-functional in Tableau Prep 2020.2.1.