IsSelectable is false for folders that are listed by the IMAP server with "\NoSelect" attribute. Whether or not the folder name contains "*" is irrelevant from Rebex IMAP's (or other IMAP client's) point of view. If any folder that contains "*" shows with IsSelectable false, that implies that the server lists those folders with "\NoSelect" attribute. And, as your log confirms (EXAMINE command is just a read-only form of SELECT command), it is actually enforcing this non-selectability.
If these folders actually do contain emails, and are not supposed to be non-selectable, this would be a server-side issue. There is nothing an IMAP client can do about it, unfortunately. It's the IMAP server that's listing those folders as non-selectable and refusing to select them.