Questions You do not have access to this entity set.

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<m:message xml:lang="en-US">An error has occurred.</m:message>
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<m:message>You do not have access to this entity set.</m:message>
<m:type>PX.Data.PXException</m:type>
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For the last few days I've been fighting with this error on a couple of my OData feeds.  The GIs work fine but when they are queried via OData they mysteriously started throwing this error.  I have the same screens on my development environment and OData worked fine there.  After trying other admin accounts, exhaustively reviewing security roles, GI changes (via audit history)  and a number of other useless changes that didn't help, I managed to figure out how to make this stop happening.  If it helps, both of the affected GIs are considered Primary List screens (Sales Orders/Payments and Applications).

This post isn't so much asking for help as it is documenting a potential fix for something I had zero luck finding an answer to online.  Google has no results for an exact search term matching the Topic title.  Neither do Stack Overflow or the Acumatica Knowledgebase.  I thought it might help someone if I shared the error, how I think it was caused and how I ended up fixing by brute force trial and error.   

How it was caused (partially/maybe):

Last week I noticed our Acumatica Site Map was kind of a mess and it was slowing down some of the work I needed to do.  I was just having a hard time locating some GIs while browsing for them with the "Inquire Title" search.  Sure I could have searched for them in the site search, but I digress...

With the help of a coworker we started moving things from the random places they ended up to where the default tree structure suggests they should live.  Among the many screens that we moved (all Generic Inquiries), the two OData feeds that stopped working were impacted.  Despite having these in the right place I believe how I moved some of the screens caused this error.  Instead of using the Generic Inquiry interface to change the location, I did a lot of cut and pasting in the Site Map screen (image attached).  

While I believe the above played some role in causing the error, I have not been able to figure out how to reproduce it.  I tried moving a regular GI around (not a Primary List screen) and it worked with OData no matter what I did.   While I really want to get to the bottom of what scenario causes this, I don't have time right now.  Maybe it is a Primary List thing, I just do not know.

An additional factor may have been using the Edit menu option in the modern UI to get missing menu elements back where they should be.  I had to do this in a number of places and I know for a fact Payments and Applications was part of these changes.  It was missing from Receivables -> Transactions as well as Sales Orders -> Transactions.  I have yet tried to reproduce the issue with a site map cut/paste and editing the menu.

How I fixed it? 

Once it dawned on me that the day these OData feeds stopped working was also the day we were working on the Site Map, I thought it had to be related to that.  Both screens had the right configuration defaults for Location, Workspace and Category when compared to my unmodified dev site map.  The Expose to OData box was still checked.  At first glance I was convinced these were both setup right.  Despite that conviction I used the Generic Inquiry screen's "Site Map Location" field to move one of them to a different location and saved it.  Then I moved it back to Primary Lists and saved it.  After the move/move back operation the OData feed started to work again.

Maybe someone has an idea for why this might occur, if so I'd love to hear it.  If nothing else I think it is entirely possible someone else might run into this some day and I hope this post saves that person a lot of time.