I have six months of PrivCards data sitting here so here is what normal looks like, for calibration.
| Month | Top-ups | Spends | Declines | Card locked |
|---|---|---|---|---|
| Jan | 3 | 22 | 1 | no |
| Feb | 4 | 31 | 0 | no |
| Mar | 2 | 18 | 2 | 9 days |
| Apr | 5 | 27 | 1 | no |
| May | 4 | 24 | 0 | no |
| Jun | 2 | 11 | 0 | no |
The March lock is the interesting row. Card showed active the whole time and declined everything the whole time, exactly what you are describing. It came back on its own, no ticket, no explanation, nine days after it started. Balance intact.
So the pattern exists and it is not fatal. I would not conclude anything about your four hundred until day ten.