My supplier feed import "succeeded" but the prices in Shopify are wrong
An import tool reports success when every row was read and written. It can't tell whether the numbers were the right ones. The usual causes:
The cost column was used as the selling price. Many supplier files have both a wholesale/cost column and an RRP/retail column. Map the wrong one and every price drops to cost.
The columns moved. The supplier added or reordered a column, so the old mapping now points at different data.
Currency or format changed. A file that switched currency or decimal style can shift every price at once.
The wrong sheet or tab was read. A different tab can have the same headers but different numbers.
Fixing it without an app
Export your products from Shopify (Products → Export) so you have the current prices.
Open the supplier file and check which column is retail and which is cost.
Spot-check 10–20 SKUs against your export before importing again.
Re-import only the corrected prices.
Catching it automatically
Fieldwork Supplier Feed Sync compares every file with your store before writing anything:
New feeds start in dry-run: you see each price, compare-at and stock change before anything is applied (compare-at updates are optional and off by default).
If more than 5% of matched items (at least 2) change price by more than 30% (the 30% is adjustable per feed), or any single price triples or falls below a third, the run is held and nothing in your store changes. The message names an example SKU and its old and new price, and says this often means the cost column was mapped as price, or a currency change.
If the file's columns changed since the last good run, the run is held until you re-confirm the mapping.
If both a retail price and a cost column are found when mapping, the app tells you so you can pick the right one.
When a run is held you get an alert (in the app, and by email when you've set an alert address). If you've checked the changes and they're real (for example the supplier did raise prices), you can approve that exact held file once. (Empty files, files that match nothing and plan-limit holds can't be approved.)
Fieldwork Supplier Feed Sync is coming soon to the Shopify App Store.