[galaxy-dev] This job is waiting to run - Issue after Update to 15.10

Dear Galaxy Community, after updating my Galaxy instance to 15.10 via Git, I encountered a strange "This job is waiting to run" issue. When starting a new job, (even reloading a successfull one) the result dataset remains in the status "This job is waiting to run" The NCBI Blast+ tools as well as the chart tools (Boxplot, Barplot and so on) are not affected. Wheras all other tools are, including Filter, Sort and the other Build in tools as well as our own developed tools. A reload of the tool config via the admin console was successfull but did´t solve the problem. Can you give me a hint how to solve this? I´m using a Ubuntu 14.04 Server, if this is of interest. Many thanks in advance!