ADBCall with "shell ls -R /sdca...*/** returns sometime

In a test script I poll a file system tree on a
HTC 10
with this command (… replaces company related text):
put ADBCall("-s FA…04 shell ls -R /sdcard/…/…////") into filesResult

But sometimes the filesResult is 0 bytes long, I loop with 1 s Wait.
Until the programmed timeout aborts it.

Sometimes after the test fails the same command in the console works.
Sometimes not.
Finally there are always folders and files in this wildcard pattern existing.

Does somebody has/had similar problems?

The ADB is 1.0.32.
eggPlant Functional 16.1.2-Windows.
The PC is a Win7 64 bit machine.

Shall I try the newest adb.exe?

I found a solution.
I assumed that the command takes too much time, if the returned tree is too huge.
Because it is a result folder structure, I simply wiped all the results.
And the command runs quickly enough.