The running Form isn't keeping consistent with "Startup object" choosing Form

[Zheng-Li01]

Minimal Reproduction Scenario

1. Create a WinForms .Net Core VB application with three Form designers, and added several controls for each Form designer
2. Go to app's Properties ->Application page
3. Switch the Form in the Startup object
4. Run the project directly -- this is necessary step.
5. Repeat the steps 3 & 4
6. Observer the results between running Form and Startup object choosing Form

Current Behavior

The running Form isn't keeping consistent with "Startup object" choosing Form

Expected Behavior

The running Form should keep consistent with "Startup object" choosing Form

Test Environment

Dev17 17.9.0 Preview 2.0 [34313.131.main]

Have you experienced this same issue with .NET Framework designer?

No

Have you experienced this same issue with previous previews of VisualStudio?

No, this issue can't reproduce on Dev17 17.7.6 which own the old template.

More Info

1. The issue can't reproduce on .NET Framework with new template.
2. The issue can't reproduce if saving before running the project.