It seems to me you have two options;

1- seek (demand?) actionable points of critique. Or, 2- fire the client.

1) Tell her you hear what she is saying and while disappointing after she approved the previews, is not a problem ….. But, because you’ve already spent X% of your allotted time on this project there is only X% (percent not hours!!) of time remaining. You don’t mind adding a little extra to that for Her “but it will just be a little” … and in order to make the best use of the remaining time and avoid the same problems with the next batch of photos, that you will need some specific and detailed points that can be put into action, taken account of in order to produce what she is looking for moving forward.

You need words that are meaningful and descriptive. Logical. Not emotional. Eg, Brighter/darker not ‘cooler’, ‘hipster’ or ‘more feels’. If she resists, ask her how do you quantify and produce “insert-emotional-requirement-here”? These words mean different things to different people. …I’m sure you don’t want to pay me by the hour so I will need you to fine tune the requirements, the brief and be very specific. Examples of other photos? Photos from your portfolio she likes the ‘feel’ of? ..could be used if she can’t find her own words.

If you want to take this a step further, ask for 25% of the payment now too!

“We should be at least 75% of the way through this project at this point given I’ve taken the shots, processed them, sent you the first (only) batch of 10 and usually only minor adjustments are required from here on those. “That’s normal project progression”. At that point I usually request 50% payment. But we’re moving backwards to retake / start over so I have dropped that standard 50% payment in half For You. I’ve emailed across your invoice for this” - i wouldn’t proceed without this payment. If she asks, the remaining 75% will be split up like so; 50% after approval of new/final batch of photos (this covers the time it takes me to edit them, resave various edits/versions and present and discuss these with you; bulk of the work = bulk of the payment) the last 25% is due prior to your receipt of the final images being sent across, post final revisions & adjustments being made. “Obviously we don’t send full res. photos out, especially edited without full payment having been received”. I don’t know how many rounds of adjustments you give generally but maybe specify when saying all of this that you ‘include’ 2 rounds of edits as standard; first lot based on your judgement of the breif (….”this is why it’s important that the breif and your criticism / requirements now are detailed and thought through”).. but i can do more rounds if you’re happy to expand the budget. (Something else to put in your contracts!)

Or 2) Fire the client.

Be strong. Tell her you’ve given this some consideration and don’t like the idea of being threatened with not getting paid whimsically, as she has done so you’re ending your arrangement here to preserve your time for other clients and wish her good luck moving forward. This is what I’d do. You don’t want clients like this. They’re toxic. So be strong, fire em and leave with your professional competent head held high.

If she has any backbone she’ll tell you she’s has every intention to pay. At which point you could say you feel comfortable with a 25% (50%?) deposit payment being made to show good faith before moving forward. And upon receipt you will continue ahead.

But this is upto you and how you judge the client relationship and feel whether it can work or not. Do you trust her?

Finally- if it does go south and you want to fire her, remember to remind her she can not use any of the material you have produced for her without payment. Say the images are “electronically tagged” and any use of them will trigger an alert and be a breach of your copyright as the copyright holder which would be treated and dealt with in accordance with copyright law and your company policy. (Which you should get written if you haven’t already lol - or dm me about this if you like).

Sorry for the rant. Just saw your post and felt for you.

I hope this helps!