SML Smart Meter Interface reads only garbage from IR-interface

[Kugeleis]

I have Tasmota with SML compiled and red an ISKRA 174 following the instructions. It used to work with an older Tasmota version. Now, after recompiling with a newer version I get readings like this:

09:30:28.446 : Io R s/Nnm??6-./�Kg'�o�'s) 9 ['/5�>sJs]==~/Nny/?lk~??u?]??1=:{i W�o?=  ??050o><3[W scw?�oGy/?''_??lF{7?*oW?� 

I tried different baud rates but nothing worked. Any ideas how to debug this issue? What could be the raeson?