Back burner maya rendering issue


first, I like to excuse for my bitter English, it’s not my mother tongue
In our company, we use back burner to set up network render, everything was going smoothly but recently
some troubles start to show up, for some shots, its first few frames get rendered fine but then render time increases for example for frame 1 pc1 took 18 minutes to render but later for frame 15 it took 56 minutes then
after some time other frames there won’t be any night this kind of shots will halt and other shots
will be pending on the queue. we tried to batch render on individual machines and its work fine. we examined problematic shots but didn’t find anything corrupted or hindering render process. our network locations are working fine and there any access issue. we didn’t have clue what went wrong.

we are looking forward to a fine solution and will be much appreciated.

maya 2017 update 4
back burner ver 2019.0.0_5 [we tried latest updates still no use]
redshift rs_v2.5.48
JoeAlter Shave And A Haircut. .2017 .v9.5v

windows 10 professional 64 bit
i7 4 GHz cpu
we use gtx 1060,1080t,1070 on various systems and every PC have 32 GB memory