Hooks on a dynamic loaded class works, sometimes not

[cryptax]

I am using malicious sample Android/Alien dc215663af92d41f40f36088ec1b850b81092ea94a4a061a9ce88178daee965a.
I want to hook in class mgcmudrfccmnwasmkd.qalnmoqsc.oygfoqispqmmjqqkuij.gjavovxatuj, which is dynamically loaded, a method private String a(String arg5).
I use:

• Start panel: an Android emulator, via USB, and package name msqqqwokejyfwim.bzsotef.ftonpdptfkkfhcjxkrr
• Hook panel: I specify the class and method name. I managed to get it to work without specifying anything more! (did not need to specify overload type nor dynamic path).

Sometimes it works.
See below.

This is good.
But sometimes (often) it does not work.
The most common error I get is [!] Process not found, trying to spawn it...
Some other times I get [!]Error: Error: java.lang.ClassNotFoundException: Didn't find class "msqqqwokejyfwim.bzsotef.ftonpdptfkkfhcjxkrr.gjavovxatuj" on path: DexPathList[[zip file "/data/user/0/msqqqwokejyfwim.bzsotef.ftonpdptfkkfhcjxkrr/app_DynamicOptDex/jeSk.json"],nativeLibraryDirectories=[, /system/lib64, /vendor/lib64]]
Note that the path /data/user/0/msqqqwokejyfwim.bzsotef.ftonpdptfkkfhcjxkrr/app_DynamicOptDex/jeSk.json corresponds to the dynamically loaded dex (unpacked).
Sometimes I get "nothing". Nothing happens.

I am unsure if this is a bug, or if I am doing something wrong, but I'd be grateful to have a solution that works 100% all the time :)