diff --git a/src/libslic3r/Print.cpp b/src/libslic3r/Print.cpp
index 7815391e9..6253f4e89 100644
--- a/src/libslic3r/Print.cpp
+++ b/src/libslic3r/Print.cpp
@@ -946,6 +946,7 @@ Print::ApplyStatus Print::apply(const Model &model, const DynamicPrintConfig &co
                 // Simple case, just generate new instances.
                 for (const PrintInstances &print_instances : new_print_instances) {
                     PrintObject *print_object = new PrintObject(this, model_object, model_object->raw_bounding_box());
+					print_object->set_trafo(print_instances.trafo);
                     print_object->set_copies(print_instances.copies);
                     print_object->config_apply(config);
                     print_objects_new.emplace_back(print_object);
@@ -959,10 +960,11 @@ Print::ApplyStatus Print::apply(const Model &model, const DynamicPrintConfig &co
             // Merge the old / new lists.
             auto it_old = old.begin();
             for (const PrintInstances &new_instances : new_print_instances) {
-                for (; transform3d_lower((*it_old)->trafo, new_instances.trafo); ++ it_old);
-                if (! transform3d_equal((*it_old)->trafo, new_instances.trafo)) {
+				for (; it_old != old.end() && transform3d_lower((*it_old)->trafo, new_instances.trafo); ++ it_old);
+				if (it_old == old.end() || ! transform3d_equal((*it_old)->trafo, new_instances.trafo)) {
                     // This is a new instance (or a set of instances with the same trafo). Just add it.
                     PrintObject *print_object = new PrintObject(this, model_object, model_object->raw_bounding_box());
+                    print_object->set_trafo(new_instances.trafo);
                     print_object->set_copies(new_instances.copies);
                     print_object->config_apply(config);
                     print_objects_new.emplace_back(print_object);
diff --git a/src/libslic3r/Print.hpp b/src/libslic3r/Print.hpp
index bd04cd371..5127b588e 100644
--- a/src/libslic3r/Print.hpp
+++ b/src/libslic3r/Print.hpp
@@ -203,7 +203,9 @@ public:
     void                    config_apply_only(const ConfigBase &other, const t_config_option_keys &keys, bool ignore_nonexistent = false) { this->m_config.apply_only(other, keys, ignore_nonexistent); }
     const LayerPtrs&        layers() const          { return m_layers; }
     const SupportLayerPtrs& support_layers() const  { return m_support_layers; }
+
     const Transform3d&      trafo() const           { return m_trafo; }
+    void                    set_trafo(const Transform3d& trafo) { m_trafo = trafo; }
 
     const Points&           copies() const { return m_copies; }
     bool                    add_copy(const Vec2d &point);
diff --git a/src/libslic3r/PrintObject.cpp b/src/libslic3r/PrintObject.cpp
index 38b2e678b..b7b33087f 100644
--- a/src/libslic3r/PrintObject.cpp
+++ b/src/libslic3r/PrintObject.cpp
@@ -1615,10 +1615,7 @@ std::vector<ExPolygons> PrintObject::_slice_volumes(const std::vector<float> &z,
         for (const ModelVolume *v : volumes)
             mesh.merge(v->mesh);
         if (mesh.stl.stats.number_of_facets > 0) {
-            // transform mesh
-            // we ignore the per-instance transformations currently and only 
-            // consider the first one
-            this->model_object()->instances.front()->transform_mesh(&mesh, true);
+            mesh.transform(m_trafo.cast<float>());
             // align mesh to Z = 0 (it should be already aligned actually) and apply XY shift
             mesh.translate(- unscale<float>(m_copies_shift(0)), - unscale<float>(m_copies_shift(1)), - float(this->model_object()->bounding_box().min(2)));
             // perform actual slicing
diff --git a/src/slic3r/GUI/Plater.cpp b/src/slic3r/GUI/Plater.cpp
index e39760184..8fdb5fd3b 100644
--- a/src/slic3r/GUI/Plater.cpp
+++ b/src/slic3r/GUI/Plater.cpp
@@ -2408,7 +2408,7 @@ void Plater::reslice()
     // Don't reslice if export of G-code or sending to OctoPrint is running.
 //    if (! defined($self->{export_gcode_output_file}) && ! defined($self->{send_gcode_file})) {
     // Stop the background processing threads, stop the async update timer.
-    this->p->stop_background_process();
+//    this->p->stop_background_process();
     // Rather perform one additional unnecessary update of the print object instead of skipping a pending async update.
     this->p->async_apply_config();
 /*