Some Panels show N/A while the query inspector shows the collected data

Hello, since the last Grafana update (2 days agao), some values on Grafana show N/A
They collect timestamps from Zabbix.
Zabbix is OK

Query Mode : Text
Format as : Time series
Vizualisation : stat panel
Last (Not Null)

The Query inspector shows it collects correctly the data :

response:Object

jsonrpc:"2.0"

result:Array[12]

0:Object

itemid:"167979"

clock:"1601455181"

value:"2020-09-30 07:16:33.830"

ns:"635309140"

1:Object

itemid:"167979"

clock:"1601462381"

value:"2020-09-30 11:15:36.320"

ns:"571741585"

2:Object

itemid:"167979"

clock:"1601469581"

value:"2020-09-30 13:17:03.007"

ns:"570835662"

3:Object

itemid:"167979"

clock:"1601476781"

value:"2020-09-30 15:15:25.940"

ns:"591871375"

4:Object

itemid:"167979"

clock:"1601483981"

value:"2020-09-30 17:16:57.280"

ns:"516539012"

5:Object

itemid:"167979"

clock:"1601491181"

value:"2020-09-30 19:15:29.613"

ns:"264870986"

6:Object

itemid:"167979"

clock:"1601498382"

value:"2020-09-30 21:16:54.597"

ns:"18904994"

7:Object

itemid:"167979"

clock:"1601505584"

value:"2020-09-30 23:16:21.850"

ns:"480790172"

8:Object

itemid:"167979"

clock:"1601512781"

value:"2020-10-01 01:15:49.547"

ns:"409051587"

9:Object

itemid:"167979"

clock:"1601519981"

value:"2020-10-01 03:15:30.530"

ns:"569059958"

10:Object

itemid:"167979"

clock:"1601527181"

value:"2020-10-01 03:15:30.530"

ns:"756721529"

11:Object

itemid:"167979"

clock:"1601534381"

value:"2020-10-01 07:15:30.340"

ns:"546997750"

id:1