Can a landlord refuse to release me from the lease even after my buyer takes over the space?

Yes, generally a landlord can refuse to release you, and this is one of the least understood parts of assigning a commercial lease. Consenting to the assignment and releasing the original tenant from ongoing liability are two separate things — a landlord can approve your buyer as the new occupant while still keeping you contractually on the hook for the lease's obligations, since a release is an extra benefit to you, not something the landlord is generally required to grant just because they've allowed the assignment to proceed.

Landlords often prefer keeping the original tenant liable, since it gives them an extra party to pursue if the buyer later defaults, at no cost to the landlord. There's rarely a legal requirement forcing them to give it up, so it typically has to be negotiated rather than assumed.

If a clean release is important to you, raise it directly and get it agreed and documented before the assignment is finalized — don't assume that approving your buyer means approving your exit too. A Treadstone business lawyer can push for this as part of the consent negotiation.