Air carrier captain reported the aircraft leveled off 1;000 feet before assigned altitudes multiple ...

Narrative:

Climbing out of ZZZ enroute to ZZZ1; ATC issued a climb clearance to FL250. The aircraft prematurely leveled off at FL240. ATC again advised us to climb to FL250 before the error was caught. I asked the first officer why the aircraft leveled off early. He stated I don't know why; but it did the same thing last week. The MCP was correctly set to 250. Later that day the aircraft again leveled off prematurely at FL360 when the MCP was set to 370. After some investigation it appears the performance data is loading the FMC with an intermediate level off altitude and not the final cruising altitude.in our case; the flight from ZZZ-ZZZ1 was planned to level off at FL240 with a later step up to FL250. The later flight from ZZZ2-ZZZ1 was planned at FL360 to zzzzz; then FL390 to ZZZZZ1. I have been out on extended leave for the last 5 months and asked the chief pilots if there was a notification to the pilots of a software change. They were not aware of any. On my commute flight from ZZZ-ZZZ1; I advised the operating crew of the report I was writing and to let me know if it did it again. They informed me after the flight that it did it again; and that they were unable to change the cruise altitude. They had to use V/south to keep the aircraft climbing to fl 250. Investigate if there was a software change and why it may not have been relayed to the pilots. My pilot monitoring should have also caught the error.

Original NASA ASRS Text

Title: Air Carrier Captain reported the aircraft leveled off 1;000 feet before assigned altitudes multiple times; and during multiple trips.

Narrative: Climbing out of ZZZ enroute to ZZZ1; ATC issued a climb clearance to FL250. The aircraft prematurely leveled off at FL240. ATC again advised us to climb to FL250 before the error was caught. I asked the First Officer why the aircraft leveled off early. He stated I don't know why; but it did the same thing last week. The MCP was correctly set to 250. Later that day the aircraft again leveled off prematurely at FL360 when the MCP was set to 370. After some investigation it appears the performance data is loading the FMC with an intermediate level off altitude and not the final cruising altitude.In our case; the flight from ZZZ-ZZZ1 was planned to level off at FL240 with a later step up to FL250. The later flight from ZZZ2-ZZZ1 was planned at FL360 to ZZZZZ; then FL390 to ZZZZZ1. I have been out on extended leave for the last 5 months and asked the Chief Pilots if there was a notification to the pilots of a software change. They were not aware of any. On my commute flight from ZZZ-ZZZ1; I advised the operating crew of the report I was writing and to let me know if it did it again. They informed me after the flight that it did it again; and that they were unable to change the cruise altitude. They had to use V/S to keep the aircraft climbing to FL 250. Investigate if there was a software change and why it may not have been relayed to the pilots. My Pilot Monitoring should have also caught the error.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1764789
Time
Date	202009
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.ARTCC
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Climb
Flight Plan	IFR
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 57 Flight Crew Type 18000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Altitude Undershoot Deviation - Procedural Clearance

Air carrier captain reported the aircraft leveled off 1;000 feet before assigned altitudes multiple times; and during multiple trips.