I'm entering my 11-character Document ID into the field, but I keep getting error message "Please enter the 11-character Document ID without spaces from your Form 1099?

Is this for a state return?   Or are you trying to e-file?   

I am encountering the same issue importing tax documents from Acorns. 

Turbo Taxes "Import From Financial Institution" window, after selecting Acorns, presents a form with two fields, Account Number and Document ID. These values are contained within Acorns 1099 statement. The Document ID on the 1099 statement has two spaces within. Turbo Tax specifies that the Document ID be entered without spaces. When I enter the Document ID without spaces, Turbo Tax responds with the error message, "Please enter the 11-character Document ID without spaces from your Form 1099".  I tried multiple times. 

There is a support number on the page to call with any issues.  It is presented as if it were a Turbo Tax customer support number, but when you dial it, it is Acorns customer service.  I explained the issue to them and they said I need to contact Turbo Tax.

I'd guess a login for a financial provider, who uses a Document ID as part of their consolidated 1099B import process.  I seem to recall that Vanguard uses that.