Environment:
Zabbix 7.4.6
Classic custom graphSteps to reproduce:

1. Use a numeric item nammed MCS updated every 60 seconds.
2. The item history contains the following values around the issue:
   - 15:38:10 → 8
   - 15:39:10 → 4
   - 15:40:10 → 8
3. Open Monitoring → Latest data → MCS → Graph.
4. The simple graph correctly displays the drop to 4.
5. Create a classic custom graph containing the same MCS item.
6. Display the same short time range, with a 1min resolution
7. The same issue also occurs with a classic custom graph containing only the MCS item.

Result:

The classic custom graph does not display the MCS value 4.

It displays MCS continuously at 8 and reports:
Min = 8

However:

• Latest data / History contains MCS = 4 at 15:39:10
• the trigger based on last()<6 correctly generated a PROBLEM event
• the simple graph correctly displays the value 4 and reports Min = 4

The displayed period is very short and the item is updated every 60 seconds.
At this scale, the graph data is not aggregated: the displayed points should correspond directly to the collected history values.

Therefore, the missing MCS = 4 value cannot be explained by trends or time aggregation.

The issue is reproducible even when the classic custom graph contains only the MCS item, so it is not related to multiple items or multiple Y axes.

See attached screenshots:
Pic_1. Simple graph showing MCS = 4 and Min = 4
Pic_2. Classic custom graph with Signal/RSSI/MCS showing MCS = 8 and Min = 8
Pic_3. Classic custom graph with MCS only showing MCS = 8 and Min = 8
Pic_4. Latest data / History showing the raw MCS = 4 value

Expected:

The classic custom graph should display the same history values as the simple graph.

Since the displayed time range is short enough that no aggregation is involved, the graph should directly represent the collected values.

For this time range it should:

• display MCS = 4 at 15:39:10
• report Min = 4