Drip Feed problem with only one Student

Hello! I faced a weird problem. We started a new course a couple of weeks ago with 20 clients. Drip feed is set to open two new units once a week - access dates are set individually into each unit. This works fine with everyone else but one Student. She has all the same settings as everyone else and she has done everything according to instructions. The first unit opens to her, others say "unit cannot be accessed". The first one is not free unit. So this is very strange, what should I do? I tried to remove her from the course and put her back, it didn't help, after that I removed her entire account and recreated it, still the same thing. Thank you!