Investment detail holdings total not match the total in the accounts List

I think I would start by looking for Placeholders. Placeholders are Quicken's attempt to identify where there are holdings discrepancies between the actual transactions in the register and what the financial institution is reporting the holdings should be. Placeholders will be included in the Holdings view for the account but they will not be included in most other areas in Quicken. That can make the Holdings look OK when in reality there is an issue that needs to be corrected.

Before checking for Placeholders I suggest going to Edit > Preferences > Investments and make sure the box is checked for Show hidden transactions.

Then if you look below the register there should be a Placeholder Entries tab. That would be the 1st place I would look for them. You can also scroll through the Account Register looking for them but that can take a little longer. If any are listed in the tab or are found in the Account Register they will need to be resolved.

Another thing you could do: Click on the Gear icon above the register and toward the right. Then click on Reconcile Shares. This will produce a popup telling you if the shares in Quicken and the shares reported by Fidelity are the same or, if not, it will provide you with some details of the difference(s).

As a final step in this 1st troubleshooting process: Click on the blue font Cash Balance dollar amount below the register toward the right. This will tell you if the dollar amount shown there and if the dollar amount reported by Fidelity are the same or not. They should be the same.

Let me know what you find out.