Recruiter taking a lot of time to release the offer

I interviewed for a US-based company, the process started during the last week of March. The process took a month to complete, and the final round took 2 weeks to get scheduled since the director of engineering was not available. After all rounds were complete, it took 2 weeks for the managing director to call me and tell me about the offer. This happened after I had to call the recruiter and ask him for updates. Since then the recruiter has taken some details in the past week and they made me sign a NDA. I called on Monday and they said they will release the offer by Wednesday as it's getting approved in the US. Now the recruiter is not picking up my calls. All this time is making me think that the recruiter is possibly considering other candidates and keeping me on hold just in case. Do you think the recruiter is ghosting me or not taking my candidature seriously? How should I proceed? Thanks!