Sometimes IDataBase.ExecuteAsync("JSON.ARRAPPEND") Doesn't Append Items to List in AWS ElastiCache Redis

Description:

We’re running into an issue with the JSON.ARRAPPEND command using StackExchange.Redis with AWS ElastiCache Redis OSS. Occasionally, when we call this command, items don’t actually get appended to the list, even though the command appears to execute without any errors. This happens randomly, so it’s hard to reproduce consistently.

var result = await IDatabase.ExecuteAsync("JSON.ARRAPPEND", [key, listPath, .. serializedItems]);
_logger.LogDebug("Redis JSON.ARRAPPEND command response: {itemsAppended}, {isNull}", result.Length, result.IsNull);

What we’ve observed:

• When this issue happens, the response shows Length 1 and IsNull False, but the items aren't actually added to the list.
• There are no exceptions or other indicators suggesting that the action has failed.
• This issue doesn't happen every time, but it’s random, making it difficult to reproduce consistently.
• We’re using AWS ElastiCache Redis OSS, and our service is deployed on AWS ECS.

Environment:

• AWS ElastiCache Redis OSS (7.1.0)
• StackExchange.Redis (2.8.16)
• .NET 8
• Deployed on AWS ECS Fargate

Any help or insight into what might be causing this issue would be greatly appreciated. Thanks in advance!

Start by reproducing JSON.ARRAPPEND through IDatabase.ExecuteAsync with AWS ElastiCache Redis OSS 7.1.0, StackExchange.Redis 2.8.16, and .NET 8, comparing the command response with the stored list. Determine why a non-null response with Length 1 can leave items unappended, and document a confirmed cause or resolution.