HaHa! I love it. Many suffer from Big Fish in Little Pond Syndrome.

Can load $297 *2 for $594 with no issues. (Using 3 unique giftcards total)
When I load $600 (3 unique GC), then attempt another load after that (different GC), it declines instantly.
Cards aren't locked up or anything. Work fine the next day (<24hr later). Doesn't even show reversals for the card.

I assume it's either an issue for the amount being over >$600 or the issue of >3 unique gift cards being used at the register in a short time?

No, this is due to the $1000 max load per 24 hours.

I sometimes run into this with OD visas, and in my case it's not the $1000 limit. E.g. do one load for $600 and a 2nd load for $400 and the 4th $200 card declines. I think it's a velocity limit on using several of the same type of card, although it doesn't seem to happen consistently. You can try shopping for 10-15 minutes and go back for the 2nd load.

I overcome this issue by loading 900 (500+200+200) p1 and p2 one after another. No issues with this method.

Thanks to poster jeffersun for tip about contactless. Tried and it worked.
-Told them I want to load money to card
-Entered Discover card, asked to key in zip code
-Remove card; told them amount
-Entered debit card, entered PIN
-Got receipt; money in Discover account instantly

In the data point spreadsheet what is 'BIN' in column F? It says it's an optional field, some people enter 8 digits, others 6.

First 6/8 digits of the VGC/MCGC

Depending on WM, the velocity limit for BHN/PW $200 cards (those that can be swiped in full) can be between 1, 2, 3 or 4 (I never tried more than four in one visit, so higher might also be possible). I have 13 WMs around me (within <30 min drive) and already know which one has which velocity limit, so I don't get denials by going over. Yours might be set to 3. I have not tested velocity for those BHN/PW cards that can only be swiped $99, interesting to hear that you could do 6 swipes in one visit. So maybe the velocity is truly by unique cards used and not by swipes (just hypothesizing).

I can do 2 cards of 3 $99 swipes each at a regular walmart no problem but can only do one card with 3 $99 swipes at a neighborhood market walmart without an error. I take a 8-10 min break and come back and complete the other card with the other 3 swipes no problem.

So unfortunately I bought a grip of $200 VGCs from OD last week during the promo. They are 435880 BINs (Pathward/BHN). I've been out of the game awhile and didn't know about the difficulties in liquidating these....
5 of them have defective mag strips (card read error at register the instant it swipes), double checked with my USB mag reader at home, 4 of them don't give any data, one scans about 1out of every 6 swipes. BHN is replacing them, would not consider cutting a check. Oof.
Since now I realize I need some more experimentation, I bought a $5 item at a Fred Meyer (Kroger) SCO this morning. I had registered the card online with name/address but did not set a PIN. Payment declined using my usual PIN and when trying the last 4 dig. Tried again as credit and it went through.
Then onto Safeway, tested my luck with another fresh, unregistered VGC. Bought oranges and a $50 Zift card at SCO (seems that all GCs at Safeway SCO need mgr override, unlike Kroger). Same issue, debit declined, credit went through.
Trying to understand these data points. Do these cards need the PIN set manually online to run as debit (unlike the Incomms I was used to)? My planned method of liquidation was WM to load discover, and MOs at Fred Meyer, so I'm mainly interested in what I need to do to get the cards to work in that context. Hopefully I can manage swipes >$99 otherwise this will be painful!
Thanks in advance.

Don't need to set pin online. You should be good to load at Walmart. Keeping to $99/swipe

OK. Going to avoid this BIN in the future. I’m assuming that if PIN debit failed at Kroger SCO that it will also fail at buying Kroger MOs (at 99/swipe) at the service counter. Not sure if that is correct or not.

435880 is also the BIN for the VGCs sold at Staples.
If you avoid them, you'll need other sources for no-fee VGCs.

I see. I saw some other packaging when I was at OD and thought they might be a different BIN. Would definitely rather be able to do swipes above $100, since 99/ swipe is a significant drag on liquidation.