Multimapping still producing very odd problems in latest RC

While searching reason for a new problem with JEvents 3.4RC5 I came across this:
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And unfortunately disabling multimapping enabled previously solved the problem.

How the problem presented:
- users (publishers child group) could not get their events to show on events calendar (setting them up via front-end)
- events were visible to super admins in backend and there was nothing wrong with them: correct publishing correct visibility group, correct priority and nothing telling even admins why they don't show
- when debugging the problem admins got a couple of hints of the problem:
1) Fatal error: Call to a member function rp_id() on non-object in /administrator/components/com_jevents/controllers/icalevent.php on line 1017
2) "Tapahtumasi on tallennettu ja odottaa tarkistusta" (Your event has been saved and is awaiting approval – needless to say publishers and above can publish their own events and the site uses Joomla ACL, not the JEvents specific ones)

The System:

PHP Version : 5.4.38

MySQL Version : 5.5.42-cll

Fix jQuery? : Yes

Load JEvents Bootstrap CSS? : Yes

Load JEvents Bootstrap JS? : Yes

Max Input Vars ? : 1000

Club code set? : Yes  

User Agent : Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:40.0) Gecko/20100101 Firefox/40.0  

Joomla : 3.4.3

component_com_jevents : 3.4.0RC5

component_com_jeventstags : 3.1.2

component_com_jevlocations : 3.4.0RC7

component_com_rsvppro : 3.2.6

component_com_jce : 2.5.2

module_mod_jevents_cal : 3.4.0RC5

module_mod_jevents_custom : 3.4.0RC5

module_mod_jevents_filter : 3.4.0RC5

module_mod_jevents_latest : 3.4.0RC5

module_mod_jevents_legend : 3.4.0RC5

module_mod_jevents_slideshow : 3.0.6

module_mod_jevents_switchview : 3.4.0RC5

module_mod_jevlocations : 3.4.0RC7

layout_extplus : 3.2.4

layout_flatplus : 3.4.0RC2

layout_iconic : 3.5.0RC2

layout_ruthin : 3.4.0RC2

layout_smartphone : 3.0.10

plugin_content_jevent_embed : 3.1.7

plugin_content_jevents : 3.4.0RC5

plugin_content_jevlocation_embed : 3.4.0RC7 (not enabled)

plugin_finder_jevents : 3.4.0RC5

plugin_jevents_agendaminutes : 3.1.9

plugin_jevents_jevcustomfields : 3.1.23

plugin_jevents_jevfeatured : 3.0.3

plugin_jevents_jevfiles : 3.0.14

plugin_jevents_jevlocations : 3.4.0RC7

plugin_jevents_jevmatchingevents : 3.2.1

plugin_jevents_jevmetatags : 3.0.2

plugin_jevents_jevnotify : 3.0.14

plugin_jevents_jevrsvppro : 3.2.6

plugin_jevents_jevtags : 3.1.2

plugin_rsvppro_authorizenet : 3.2.6 (not enabled)

plugin_rsvppro_manual : 3.2.6

plugin_rsvppro_paypalipn : 3.2.6 (not enabled)

plugin_search_eventsearch : 3.4.0RC5

plugin_search_jevlocsearch : 3.4.0RC7

plugin_system_gwejson : 3.4.0RC5

plugin_system_hika_rsvp_redirect : 3.2.6 (not enabled)