Will my ERB automatically reflect promotion from E3 to E4 at 24 months, even though I am flagged?

No, you cannot be promoted while you are flagged, that's why a flag is known as a suspension of favorable actions. Once you recover from your flag you will be promoted.. You can find all the references in AR 600-8-19

SFC (Join to see) and MSG (Join to see) both answered greatly. I don't know why this has been popping up so much lately. Promoting form PFC to SPC is not "automatic".

It is almost always a circle yes, but the commander has to circle yes or no for anyone coming up on the requirements met. With you being flagged, you will be circled no until it is lifted and the issues resolved.

For just pay, you will receive the 2-year pay bump which may help your struggles.

One way to avoid having financial struggles is to not be flagged for 8 months. It only becomes an emergency when your going broke? How about not doing whatever it is you did to be flagged? Or if you are flagged, correct whatever it was in less than 8 months? Smh!!!!

You will probably get a longevity pay raise...but you will not get new rank pay raise until you get unflagged and advanced to SPC. Your ERB will NOT change. It will continue to read PFC until you are advanced. And again, you will not be advanced until you are unflagged and your Commander approves your 4187 advancement to SPC.

Ok, few misconceptions to clear up for you.
You are flagged. Which means any favorable personnel actions are suspended. You will not get promoted in any sense of the word, you will have no schools, no awards. You are stuck in a limbo state until that flag is removed. Once it is and you are still in the Army then yes, you will get promoted, not until.

Also, there is no automatic or required promotion. You reach certain markers in TIG and TIS and you enter a window in which you are eligible to be promoted. It still requires your Commander to initiate the paper work to promote you. And as long as you are flagged, no commander will do that.

As stated, you will not be promoted until you are unflagged. Get unflagged. Time now.

If your S1 did everything right it will not change. Only your pay increase due to time in service. Just learn from the experience, recover, and excel from this point in!

If you are flagged your not eligible for promotion.

Let be a clear on this so your fully understanding. A flag is a slow chapter from the Army by another means. It means you cannot enlist again in the Army while it is in place, you cannot reclass, you cannot get any medals or certs of achievement no matter how hard you work. Hopefully someone told you that much. I won't repeat what the others said other than to say it takes a while for a FLAG to be lifted after your 1SG initiates action. So by waiting 8 months, if your 1SG jumps right on it (unlikely unless you push hard for that) your going to wait probably another 30-45 days before it is lifted. Your 1SG is probably pizzed at you already for sitting on it. That's why you shouldn't wait on items like this. Last but not least, never sit back and rely on the Army's automatic promotion system, you should be pushing to get promoted ahead of schedule with waivers. Wow and your a Cav Scout on top. Your direct leadership hasn't sat down to talk to you about the FLAG and it's repercussions yet? If they have, why haven't you acted? Cav Scouts and Infantrymen generally get two waivers of promotion prior to SSG, so I hate to tell you this but you are behind your peer group right now on promotions more than likely. Not a good place to be when the next draw down happens.

My husband was in this exact situation. His did not show up on his ERB but he did notice a pay increase. Hope that helps. It also might vary on the situation