Welcome! This forum has a treasure trove of great info – Scouters helping Scouters! Just a heads up, though - all content, information, and opinions shared on this forum are those of the author, not the BSA.
I am having difficulty inviting a merit badge counselor for a scout. After selecting the counselor, the “merit badge counselor” option is grayed out. The counselor is listed in the latest edition of our district’s MBC list. Here is a screen shot if it helps.
How are you finding them in the Scoutbook MBC list? Searching by name? What MBs are listed for them in the MBC list? If they’re not appearing, it’s possible that either council hasn’t correctly listed them in Scoutbook/Akela/etc with their MBs, or they might have multiple BSA IDs/accounts.