I have seen that many changes in yowsup (V.2.4) have been made, Protocol-Update (S40 env to 2.12.96), E2E-Encryption enabled etc... This Changes are not implemented in Whatsup 1.2.7 and these are perhaps the causes of problems currently?
https://github.com/tgalal/yowsup/releases/tag/v2.4