Sending files with recursive = yes creates wrong first level subdirectories (first letter is missing)

If I have a tree

./aa/bb/b1.txt
./aa/bb/b2.txt
./aa/a1.txt
./aa/a2.txt
./1.txt
./2.txt

in the source directory and I will send these files with the parameter 'recursive=yes' then I get

./a/bb/b1.txt
./a/bb/b2.txt
./a/a1.txt
./a/a2.txt
./1.txt
./2.txt

in the target directory