Yes, you do need to file the Maryland form 510. This is what Maryland states:
Every Maryland pass-through entity must file a return on Form 510, even if it has no income or the entity is inactive. You will enter a lot of zeros on this form.
The good news is that you can complete it online:
https://forms.marylandtaxes.gov/current_forms/510.pdf
Here are the instructions:
https://forms.marylandtaxes.gov/current_forms/PTE_Booklet.pdf
File Form 510 by the 15th day of the 4th month following the close of the tax year or period. The return must be filed with the Comptroller of Maryland, Revenue Administration Division, 110 Carroll Street, Annapolis, Maryland 21411-30001.
You may file your Maryland Corporation or Pass-Through Entity returns electronically using the Modernized e-File method of Federal/State 1120/1065 filing. For more information, contact our e-File Help Desk at 410- 260-7753 or visit www.marylandtaxes.gov
If you have other questions about this, ask in the comment section below.