Some people believed that in order to take advantage of tax treaty provisions that required you to be a resident of the other country before coming to the US, that it means you must have been in that country for at least a year right before coming to the US in the status that qualifies for the tax treaty provision. In your case, you only went back to the country for 2 months, and before that you were in a status that didn't qualify for the tax treaty provision.
However, there was an IRS opinion that said that someone from China who was first in the US as an F1 student, who then did a Change of Status to a J1 teacher/researcher, was eligible for the tax treaty provision for teacher/researcher despite not having been back to China for one year between their F1 and J1 statuses. The opinion relied on the language of the particular article of the US-China tax treaty, which required that the person "is, or immediately before visiting a Contracting State was, a resident of the other Contracting State" (which this person was, before coming to the US on F1), and that the person "is temporarily present in the first-mentioned Contracting State for the primary purpose of teaching ..." (which the person was), without explicitly requiring that the person was a resident of the other state immediately before teaching/researching in the US.
Article 21 paragraph 2 of the US-Bangladesh tax treaty, which is the section that deals with tax exemption for students, contains the same language, e.g. that the person "was a resident of a Contracting State immediately before visiting the other Contracting State" (which you were, before you came to the US on F2) and that the person "is temporarily present in that other State for the primary purpose of ..." (which you are) without requiring that the person be a resident of the other state immediately before being a student in the US. So I think the logic of that opinion should apply equally to the US-Bangladesh tax treaty exemption for students.
There are some differences between your case and the one in the opinion, e.g. you did go back to Bangladesh for a short period of time, whereas the person in the opinion did a Change of Status in the US without going back, but I think that, logically, it shouldn't be harder to claim the tax treaty exemption for someone who has gone back to the country for a short time than for someone who didn't go back at all. I am not sure how you would get GLACIER to allow it however.