I appreciate you for reporting this issue in the Community, @Twi .

Upon checking on my end, our Product Engineers are working on a fix for the error you've encountered as of posting. However, I can still guide you through possible solutions to resolve this and route you to our Support Team if the problem persists. 

This issue is usually system-specific, and I highly recommend collaborating with your IT expert for the steps outlined below. 

One fix we can perform is to register the ShipRush OCX file. 

1. Click on the Windows Start menu and select All Programs. Then, select Accessories.
2. Right-click on Command Prompt and choose Run as Administrator.
3. In your command prompt window you need to type this command to change your working directory and after that press Enter:
      a. cd c:\Windows\syswow64
4. You need to type the following command in your command prompt window and press Enter to register the ShipRush file:
      a. regsvr32.exe “c:\Program Files (x86)\Common Files\Intuit\ShippingManager\ZRush_ShipRush9_QB.ocx”
5. Click OK on the message that is displayed. 
6. Reboot the computer and set up Shipping Manager again.

If this doesn't work, rename the Shipping Manager folders. You can follow these steps:

1. Browse to the following folders in Windows File Explorer:
      a. C:\Program Files (x86)\Common Files\Intuit\ShippingManager
      b. C:\Users\[WindowsUserName]\AppData\Roaming\Intuit\ShippingManager
2. Right-click on the folder name, choose Rename and add OLD to the end of the name (…ShippingManagerOLD).
3. Repair/Reinstall QuickBooks.
4. Reboot the computer even if not prompted. 
5. Set up the Shipping Manager again. 

If you encounter the same problem shipping after the steps above, I'd recommend contacting our Support Team for further assistance. This way, you'll also be notified once the error you encountered is resolved. Here's how you can reach out to them:

1. In your QBDT, go to Help, then select QuickBooks Desktop Help/Contact Us.
2. Select Contact Us. Give a brief description of your issue, then click on Continue.
3. Sign in to your Intuit account, select Continue and Continue with my account.
4. We'll email you a single-use code. Enter your code and select Continue.
5. Select to Have us call you.

If you need a guide for setting up and managing your inventory after the issue is resolved, let me add this article as a reference: Set up Advanced Inventory in QuickBooks Desktop. 

We'll be here in the Community if you have further updates on the error you encountered when shipping within the QBDT system. We'll do our best to assist.