You are missing a bunch of interface property assignment, example below:
add_interface s1 avalon end
set_interface_property s1 addressunits symbols set_interface_property s1 associatedClock clock
set_interface_property s1 associatedReset reset
set_interface_property s1 bitsPerSymbol 8
set_interface_property s1 burstOnBurstBoundariesOnly false
set_interface_property s1 burstcountUnits WORDS
set_interface_property s1 holdTime 0
set_interface_property s1 linewrapBursts false
set_interface_property s1 maximumPendingReadTransactions 0
set_interface_property s1 maximumPendingWriteTransactions 0
set_interface_property s1 readLatency 0
set_interface_property s1 readWaitTime 1
set_interface_property s1 setupTime 0
set_interface_property s1 timingUnits Cycles
set_interface_property s1 writeWaitTime 0
set_interface_property s1 ENABLED true
If you are missing the above assignment, the slave is treated as WORD by default. Do add the above code into your hw.tcl. Modify the properties as necessarily, read latency and etc.