Apply this patch:
```
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index dfa65aaad..7561b9979 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -336,6 +336,7 @@ def initialize_datadir(dirname, n):
f.write("rpcport=" + str(rpc_port(n)) + "\n")
f.write("listenonion=0\n")
f.write("usecashaddr=1\n")
+ f.write("magneticanomalyactivationtime=1\n")
return datadir
```
Then run the test:
`./test_runner.py bip68-sequence`
Running the test fails without the fix and passes with it.