Haven't seen any complaint about that.  What exactly does the diagnostic say?

It's an *informational* diagnostic.  It implies there 'might' be a problem with efiling; that it might slow down processing.  I get it all the time with those liberated women who insist on hyphenating their last names ( I AM in CA after all 😂) 

It has never caused a problem...

I got the very same information diagnostics today, 2/17/2020.

Ref #4557 Anyone getting Taxpayer's name being truncated in the e-File? On the forms, it looks fine. Client used the same name prior year. 

Client filing married filing jointly using the same names as last year and I didn't have a problem; e-filed OK.  This is the first time I've seen this message (see above):  I don't know how to clear the diagnostic to file the return?  Any help is greatly appreciated.  Thanks.

Just ignore the diagnostic.. It doesn't interfere with e-filing.

If you have not already, you need to disable efile diagnosis for the specific client. 

• Click on Client 
• Efile Tab
• Efile Support tools
• Diable Efile Error 

Then you should be able to e-file