Scroll bar disappears in scroll view

[Webmaster4o]

I was just playing around with things, and I modified one of @omz's gists to allow infinite scroll. I noticed when more colors are added at the bottom, sometimes the scrollbar disappears and doesn't come back even when I scroll again. I'm using this code:

import ui
from random import randint
import console
import clipboard
# Generate some random hex colors:

colors = ['#%X%X%X' % (randint(0,255), randint(0,255), randint(0,255)) for i in xrange(50)]
offset = 0
class SVDelegate (object):	
	def scrollview_did_scroll(self, sv):
		scroll = sv.content_offset[1]
		#how far you can scroll before hitting the bottom
		maxscroll = 0
		for sub in sv.subviews:
			maxscroll += sub.height
		sv.content_size = 0, maxscroll
		#see if user is within 500 pixels of end of scroll
		if scroll > maxscroll-sv.height-500:
			print 'change'
			colors2 = ['#%X%X%X'%(randint(0,255),randint(0,255),randint(0,255)) for i in xrange(50)]
			for i, c in enumerate(colors2):
				swatch = ui.Button(frame=(0, i*80+maxscroll, 400, 80), background_color=c)
				swatch.flex = 'w'
				swatch.action = tapped
				sv.add_subview(swatch)
			
#Add buttons for all the colors to a scroll view:
scroll_view = ui.ScrollView(frame=(0, 0, 400, 480))
scroll_view.content_size = (0, len(colors) * 80)
scroll_view.delegate = SVDelegate()

def tapped(sender):
	r, g, b, a = sender.background_color
	hex_color = '#%X%X%X' % (int(r*255), int(g*255), int(b*255))
	clipboard.set(hex_color)
	console.hud_alert(hex_color + ' copied')


for i, c in enumerate(colors):
	swatch = ui.Button(frame=(0, i*80, 400, 80), background_color=c)
	swatch.flex = 'w'
	swatch.action = tapped
	scroll_view.add_subview(swatch)
scroll_view.name = 'Random Color Picker'
scroll_view.present('sheet')

Can anyone else replicate this behavior?