Projects and sequences get closed when switching between Workspaces

When you save a Workspace, it also saves how many Timeline and Project panels are open. All of the default workspaces in Premiere are designed to display one Timeline and one Project Panel.

If you want to keep your sequences and Project panels open, start by opening the maximum number of sequences and Project panels you need. Then, go to Window > Workspaces > Save Changes to this Workspace. Just a tip: don’t open too many—saving a Workspace with 100 sequences can slow down workspace switching.

If you create a workspace with 20 timelines and multiple Project panels, and you have all of them open, it won’t close any of them. If you have fewer timelines or Project panels open, it won’t add any extras.

However, remember that workspaces in Premiere are always being updated, even if you don’t manually save them. So, if you created a workspace with 20 timelines and multiple Project panels but then closed some, the next time you switch to that workspace, it will only allow for the number of panels you last had open.

The good news is that switching workspaces doesn’t technically "close" those panels; it just doesn’t display them. If you go to Window > Workspaces > Reset to Saved Layout (shortcut Option/Alt + Shift + 0), it will ensure all your open Timeline and Project panels are displayed.

TLDR:

• Switch to a workspace
• Open 10-30 sequences in the Timeline and the maximum Project panels you need
• Go to Window > Workspaces > Save Changes to this Workspace
• If you close a timeline or Project panel, it will reduce the number of panels the Workspace will display. However, Window > Workspaces > Reset to Saved Layout (shortcut Option/Alt + Shift + 0) will restore all open sequences and projects.

I've had this issue for years, and productions is no different. I routinely 'Reset to Saved Layout', and have it hotkeyed, but it will randomly close a bunch of timelines, and move my project panels to different areas, even if I am resetting to the same layout with minial space adjustments. It's something I have gotten used to, but it is a problem. However, it should not be closing projects. It may be causing a 'ghost project', where a project is open, but can only be seen when going to Window>Projects>. There, you might see the project open without a checkmark, indicating that premiere has closed the panel in stead of moving it, but the project remains open and hidden.

in windows OS kernals are used to open more than one program at a time... basically the computer is saying, " oh, I have to open another program, so I have to pretend I am more than one computer ( kernal ? ).

This works pretty good for simple stuff but with editing the resources needed get very demanding on your computer memory, resources, etc. I think.

If you are openening 10 projects at a time to edit ten movies at the same time I am astounded at your brilliance to be a creative editor !

Maybe keep it down to only editing 2 movies at once and see how that goes ??

Try resetting the preferences:
https://community.adobe.com/t5/premiere-pro/faq-how-to-reset-trash-preferences-in-premiere-pro/td-p/8236158?page=1

If that doesn't work, try resetting the Workspaces:
Reset a workspace
Reset the current workspace to return to its original, saved layout of panels.
1. Do one of the following:
• Click the Workspace menu icon and select Reset to Saved Layout.
• Choose Window > Workspace > Reset to Saved Layout.
from here:
https://helpx.adobe.com/premiere-pro/using/workspaces.html

If that doesn't work, try Preferences > Audio Hardware and set Input to None.

I wonder if you switched to using Premiere Pro Productions would help you with this. It was built to help with multi-project workflows. https://blog.adobe.com/en/publish/2020/04/14/introducing-productions-in-premiere-pro.html#gs.s67x1r