@Rachel Yaghoubzadeh, I'm so glad you asked. I actually put a ticket in for this because I thought it was creating a problem with bringing my modeled objects into a report. However, my problem was just because I didn't update my workspace after creating a new modeled table.
This issue is actually happening with many folks that upgraded and is just a benign error. It's not really having an impact but is a concern because you wouldn't know if you really did have an invalid object identifier.
This will be resolved in the next release 12.9.5.
Are you noticing anything other than just the error notification?
#CostingStandard(CT-Foundation)