Fix non-final sequence and nLockTime

src/wallet/asyncrpcoperation_shieldcoinbase.cpp

@@ -225,7 +225,7 @@ bool ShieldToAddress::operator()(const libzcash::SproutPaymentAddress &zaddr) co
     for (ShieldCoinbaseUTXO & t : m_op->inputs_) {
         CTxIn in(COutPoint(t.txid, t.vout));
         if (t.amount >= ASSETCHAINS_TIMELOCKGTE)
-            in.nSequence = 0;
+            in.nSequence = 0xfffffffe;
         rawTx.vin.push_back(in);
     }
     m_op->tx_ = CTransaction(rawTx);
@@ -272,8 +272,8 @@ bool ShieldToAddress::operator()(const libzcash::SaplingPaymentAddress &zaddr) c
     for (auto t : m_op->inputs_) {
         if (t.amount >= ASSETCHAINS_TIMELOCKGTE)
         {
-            m_op->builder_.SetLockTime((uint32_t)(chainActive.Height() + 1));
-            m_op->builder_.AddTransparentInput(COutPoint(t.txid, t.vout), t.scriptPubKey, t.amount, 0);
+            m_op->builder_.SetLockTime((uint32_t)(chainActive.Height()));
+            m_op->builder_.AddTransparentInput(COutPoint(t.txid, t.vout), t.scriptPubKey, t.amount, 0xfffffffe);
         }
         else
         {

src/wallet/rpcwallet.cpp

@@ -4487,7 +4487,7 @@ UniValue z_shieldcoinbase(const UniValue& params, bool fHelp)
     // (used if no Sapling addresses are involved)
     CMutableTransaction contextualTx = CreateNewContextualCMutableTransaction(
         Params().GetConsensus(), nextBlockHeight);
-    contextualTx.nLockTime = nextBlockHeight;
+    contextualTx.nLockTime = chainActive.LastTip()->GetHeight();
 
     if (contextualTx.nVersion == 1) {
         contextualTx.nVersion = 2; // Tx format should support vjoinsplits