You have taken the right steps including the excess deferral on your 2018 Tax Return.

At this point, I think you are running into an e-filing issue within TurboTax.  An update to fix the issue is expected to be released around 4/5/2019.  You can check out this TurboTax FAQ for more information: Excess 401(k) Contribution Preventing E-filing.

Be sure to sign up for updates to be alerted as soon as there is a solution.  If you do not want to wait for an update, you have the option to paper file your tax returns as this is only an e-filing issue.

Has this been fixed?

Apparently not.  I just fell afoul of it today (in TurboTax Online, per this thread;  the FAQ cited above and the various other discussions about this aren't always clear whether they pertain to TurboTax Online, or to the desktop fat-client versions, or to both).  Either way...  aaargh.

Today is April 10. This bug is not fixed yet. I definitely need to e-file this year. Please help!!

Has this issue been fixed yet?

Not even faintly (unless it has magically changed since I tried last night).  Today I admitted defeat and snail-mailed my returns (both Federal and State, since once TurboTax disabled E-file for Federal it also did so for California).  I particularly like (NOT) the way that all this only really became clear after TurboTax had charged my credit card.  At this point I am, er, definitely not a satisfied customer.