"An issue with the Data Model is preventing Microsoft Excel from opening this workbook. Try restarting Microsoft Excel." || "Powerpivot is unable to load the Data Model"

Hi,

I'm encountering the following errors preventing me from effectively using/updating my file. Powerpivot works ok in other files, so it seems isolated to this particular file; feels like the Data Model is corrupt and in need of repair.

Errors given

When I try to do anything that uses the Data Model (click on a pivot table using Data Model data, refresh a query, etc..): "An issue with the Data Model is preventing Microsoft Excel from opening this workbook. Try restarting Microsoft Excel."

When I click on PowerPivot|| Manage: "PowerPivot is unable to load the Data model."

File Description

This is a robust model, ~250mb that has taken many many hours to construct and maintain. The Data Model uses powerquery to import data from multiple excel files whose tables are then related to one another off of which calculated columns and measures are built. The 'master' data table consists of ~50 million records which is summarized in a worksheet via pivot table for use throughout the file using a variety of lookups, etc..

What I've tried so far

I've found similar posts in forums such as these but the recommended fixes have not yet worked. I've thus far:

• rebooted
• performed a quick repair to Office
• performed an online repair to Office
• disabled powerpivot, then re-enabled
• used a different machine
• tried to insert a pivot table from data model, but get first error above
• tried to refresh query, get first error above
• I am able to open PowerQuery editor, but then get the first error above
• I need to maintain the Data Model, so I can't delete the /xl folder when opening as a zip file (as recommended hereand other places)
• I'm not using SQL server
• checked to ensure Office was up to date

Product info:

Device name

Full device name

Processor 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz 3.00 GHz

Installed RAM 32.0 GB (31.7 GB usable)

Device ID

Product ID

System type 64-bit operating system, x64-based processor

Pen and touch No pen or touch input is available for this display

Edition Windows 10 Enterprise

Version 21H2

Installed on ‎11/‎17/‎2021

OS build 19044.1526

Experience Windows Feature Experience Pack 120.2212.4170.0

Please help,

Avi