Agree with above. Some BGOs take being a BGO as their full-time job. Some (not all) of those folks are retired and this is their "thing." They have lots of time to contact candidates, conduct long interviews, do a lot of follow-up, etc. Other BGOs have full-time jobs or family responsibilities. They may travel frequently. They may have personal issues. Not excuses but reality. Those folks are not less committed -- just are trying to balance many things of which their BGO duty is but one. They occasionally may need a bit of "nudging." Most (sadly, not all) will respond promptly when nudged.
Remember, too, that you probably check your portal daily. And there's just you. BGOs may not check their system daily and they may have upwards of 20 candidates. Thus, the BGO may not immediately notice a change in your status.
So, if you've been at >50% for a week or two, I would politely reach out to your BGO and let him/her know. That should trigger some action. If it doesn't, try again in another week or two. Remain polite and respectful.
BGOs take different views WRT submitting interviews. If a BGO has many candidates and it's early in the year, the BGO might wait until he/she has interviewed several to have a better sense of where the first one or two "rank" (so to speak). IOW, the first candidate seemed great but the next couple could be even more spectacular -- or not -- and the BGO wants to know that before submitting. Other BGOs do the write up that day and submit it right away. If your packet isn't 100% complete and the interview is outstanding, be patient. If you are o/w 100% complete AND it's been several weeks since your interview, a polite note to your BGO may be in order.
As someone above said, lack of a submitted BGO interview will NOT derail your application. If you're one of the very unfortunate few who has this happen, it will be frustrating. But, it won't hurt you.