2020 Silverado 1500 5.3l 10sp slips between 1st and 2nd

[Roch]

Anybody experienced that first time your truck is used of the day when you start out it slips between 1st and 2nd gear and goes through the rest of gears fine. After the first time driving after it slips it doesn’t happen again until truck sits overnight? 
thanks Rich 

[Gangly]

 

#16-NA-361: Information on Transmission Harsh 1-2 Shift Upon First Start Up/Shift of the Day Under Light Throttle - (Jan 26, 2022)

 

Condition	Some customers may comment that the transmission exhibits a harsh 1-2 shift on the first shift of the day, typically under light throttle.
Cause	This condition is due to the initial clutch fill time of the 2-3-4-6-8 (C4) clutch.
Information	Some customers may experience a flare condition on the first 1-2 shift of the day or after the vehicle has been parked for several hours. The condition may have developed after the replacement of a complete transmission assembly or the replacement of the stator support to correct a delayed engagement condition. This is most likely to occur under light throttle conditions. Subsequent 1-2 shifts have acceptable shift feel. Replacing transmission components will not correct the condition.
Correction	Important: Replacing transmission components or complete assemblies will not improve the condition. The first 1-2 shift of the day may be harsh. The customers’ vehicle should be compared to a like vehicle under the same driving conditions. Do Not replace any parts for this condition. Note: This condition will not impact the designed performance or reliability of the vehicle.

Edited June 28, 2022 by Gangly

[SilveradoRST]

7 hours ago, Gangly said:

 

#16-NA-361: Information on Transmission Harsh 1-2 Shift Upon First Start Up/Shift of the Day Under Light Throttle - (Jan 26, 2022)

 

Condition	Some customers may comment that the transmission exhibits a harsh 1-2 shift on the first shift of the day, typically under light throttle.
Cause	This condition is due to the initial clutch fill time of the 2-3-4-6-8 (C4) clutch.
Information	Some customers may experience a flare condition on the first 1-2 shift of the day or after the vehicle has been parked for several hours. The condition may have developed after the replacement of a complete transmission assembly or the replacement of the stator support to correct a delayed engagement condition. This is most likely to occur under light throttle conditions. Subsequent 1-2 shifts have acceptable shift feel. Replacing transmission components will not correct the condition.
Correction	Important: Replacing transmission components or complete assemblies will not improve the condition. The first 1-2 shift of the day may be harsh. The customers’ vehicle should be compared to a like vehicle under the same driving conditions. Do Not replace any parts for this condition. Note: This condition will not impact the designed performance or reliability of the vehicle.

 

I think this TSB was for the 8 speed.  
 

OP has the 10 speed.