If data is missing from my SRB/ERB, is something wrong with the system? Will this affect my promotion eligibility for September?

It is a system glitch. It happens because of the new system they are rolling out to replace the SRB called IPPSA (that's not exactly how it's spelled).
Basically, the information in the second system is sometimes incomplete or incorrect. You simply have to go to S1 and have them re update you're SRB. I don't know if this affects your promotion points worksheet

Great information provided. I've been retired a few years so verify with S-1 if you're still a little concerned a non accusatory letter to the president of the board pointing out brief facts of what has been submitted then disappeared and or reappeared. That you only want to be sure it's up to date for the board. It's not to whine nor brag however it shows an interest in your career to the board that shouldn't hurt. If that's only for Officer promotion boards I did say check with S-1/ Personnel folks! Good luck! We can always use more good NCOs in Allied Trades! HOOAH!

It all depends where you look. I have seen link where it shows the same form filled out some more than others. It all depends which link. Check with your S1, they can get you an official copy. I looked up my Soldiers record brief because I was going to go on a 2-month ados tour and it was missing important information and I freaked out because I was concerned that my CGSOC wouldn't be in my board file. The board had the correct Soldier record brief. Check with your S1 and get a certified copy emailed to you. I kind of went to the same problem you did and I noticed a different military websites have different information on your military history. It was confusing as hell for me! I'm sure you will get the proper report with all the proper schools annotated.